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We report on the effect of α-Fe₂O₃ phase in the magnetic properties and magnetic interactions in nickel ferrite (NiFe₂O₄-NFO) nanoparticles synthesized by co-precipitation method. Structural analysis confirms the formation of the cubic inverse spinel phase without any impurities for the NFO sample annealed in air at 650 °C. When the annealing temperature is increased to 750 °C and 850 °C, α-Fe₂O₃ impurity phase is formed along with the parent NFO phase. Raman spectra recorded at room temperature (RT) confirm the presence of pure NFO phase for the sample annealed at 650 °C, and presence of α-Fe₂O₃ phase is observed in the samples annealed at 750 °C and 850 °C. Saturation magnetization values at RT for the NFO samples annealed at 650 °C, 750 °C and 850 °C are 34 emu/g, 19 emu/g and 28 emu/g respectively. Zero Field Cooled (ZFC) and Field Cooled (FC) measurement reveals the super-paramagnetic behavior along with competing magnetic interactions in all the samples. For the NFO sample annealed at 750 °C and 850 °C, a drop in ZFC magnetization and a small kink in FC magnetization observed around 245 K indicate the presence of a Morin transition (TM) from the α-Fe₂O₃ phase. Anisotropy constants were calculated for all the samples using the law of approach to saturation (LAS) method. The magnetocrystalline anisotropy energy distribution function for the NFO samples annealed at 750 °C and 850 °C exhibit broad peak due to the random distribution of spins associated with different particle size.

We have synthesized graphene-oxide (GO) by the modified hummer's process and subsequently reduced it with gold-nanoparticles (Au-NPs) using silica coated colloidal Au-NPs and hydrazine monohydrate solutions to form r-GO:Au-NPs nanocomposites. We have studied the microstructure, electronic, electrical and magnetic properties of r-GO and r-GO:Au-NPs nanocomposites. We have observed from the Raman spectroscopy that the intensity of D-peak (disorder) gets reduced with respect to G (graphite-cluster) in r-GO:Au-NPs composites. The reduction of ID/IG ratio obtained from Raman spectra [r-GO: 1.22 → r-GO:(Au-NPs)4.88: 0.98] clearly indicates that the sp2-cluster is reduced in r-GO:Au-NPs nanocomposites. The reduction of sp2-cluster and/or enhancement of sp3-cluster is due to replacement of sp2-cluster by the Au-NPs. This observation also observed from the X-ray absorption near edge structure (XANES) spectroscopy, X-ray photoelectron spectroscopy (XPS) measurements that are consistence with reduction of conductivity as we observe from the current (I) - voltage (V) characteristics of the nanocomposites. Magnetic M-H hysteresis loops show the magnetization is enhanced in r-GO:Au-NPs nanocomposites. We believe that the reduction of conductivity and enhancement of magnetization of r-GO:Au nanocomposites would be most suitable for ferro-electro-magnetic materials for the memory storage device applications.

We report on magnetocapacitance, spin dynamics through AC succeptability measurements and dielectric anomalies in 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite. Structural studies (purity and phase) and surface morphology of the 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite were examined by X-ray diffraction (XRD), Raman Spectra, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). TEM and SEM images indicate the uniform distribution of nanoparticles in parent pahase as well as in the composite. Energy dispersive X-ray (EDX) analysis indicates the presence of Ni, Fe, O and Bi elements in 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite. Magnetization measurements were performed at 300 K, 50 K and at 2 K and the Field Cooled (FC) and Zero Field Cooled (ZFC) measurements were carried out from 350 K to 2 K. ZFC and FC magnetization curves exhibit a hump around 30 K indicating the existence of competing magnetic interactions and possible spin galss behaviour. AC succeptibility measurements at various frequencies confirm the spin glass freezing behaviour of 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite around 25 K with the relaxation time and activation energy in the order of 10−7 s and 0.938 meV respectively. The dielectric constant and dielectric loss at various frequencies and temperatures indicate the dielectric relaxation behaviour of 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite. A rapid increase in the dielectric constant near the antiferromagnetic transition temperature (TN ∼ 643 K) of BiFeO3 indicates the existence of magneto-electric coupling in this composite. Magnetocapacitance (MC) of 0.3NiFe2O4 – 0.7BiFeO3 composite was measured at room temperature and the MC values of 13.5% and 7.8% (at 5000 Oe) are observed when the pellet is perpendicular and parallel to the magneticfield direction respectively. The presented magnetic and dielectric studies reveal the existence of magnetoelectric coupling and spin glass frezing of 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite.

We report the signatures of dynamic spin fluctuations in the layered honeycomb ${\mathrm{Li}}_{3}{\mathrm{Cu}}_{2}\mathrm{Sb}{\mathrm{O}}_{6}$ compound, with a $3d S=1/2 {d}^{9}\phantom{\rule{4pt}{0ex}}{\mathrm{Cu}}^{2+}$ configuration, through muon spin rotation and relaxation ($\ensuremath{\mu}\mathrm{SR}$) and neutron scattering studies. Our zero-field (ZF) and longitudinal-field (LF) $\ensuremath{\mu}\mathrm{SR}$ results demonstrate the slowing down of the ${\mathrm{Cu}}^{2+}$ spin fluctuations below 4.0 K. The saturation of the ZF relaxation rate at low temperature, together with its weak dependence on the longitudinal field between 0 and 3.2 kG, indicates the presence of dynamic spin fluctuations persisting even at 80 mK without static order. Neutron scattering study reveals the gapped magnetic excitations with three modes at 7.7, 13.5, and 33 meV. Our density functional theory calculations reveal that the next-nearest-neighbor (NNN) antiferromagnetic (AFM) exchange (${J}_{\text{AFM}}=31$ meV) is stronger than the NN ferromagnetic (FM) exchange (${J}_{\text{FM}}=\ensuremath{-}21$ meV), indicating the importance of the orbital degrees of freedom. Our results suggest that the physics of ${\mathrm{Li}}_{3}{\mathrm{Cu}}_{2}\mathrm{Sb}{\mathrm{O}}_{6}$ can be explained by an alternating AFM chain rather than the honeycomb lattice.

Reduced dimensionality offers a piece of crucial information in deciding the type of the quantum ground state in heavy fermion materials. Here we have examined the stoichiometric ${\mathrm{CeCo}}_{2}{\mathrm{Ga}}_{8}$ compound, which crystallizes in a quasi-one-dimensional crystal structure with Ga-Ce-Co chains along the $c$ axis. The low-temperature behavior of the magnetic susceptibility ($\ensuremath{\chi}\ensuremath{\sim}{T}^{\ensuremath{-}0.2}$), heat capacity (${C}_{p}/T\ensuremath{\sim}\ensuremath{-}lnT$), and resistivity ($\ensuremath{\rho}\ensuremath{\sim}{T}^{n}$ with $n\ensuremath{\sim}1$) strongly confirms the non-Fermi liquid ground state of ${\mathrm{CeCo}}_{2}{\mathrm{Ga}}_{8}$. We study the low-energy spin dynamics of the ${\mathrm{CeCo}}_{2}{\mathrm{Ga}}_{8}$ compound utilizing zero-field (ZF) and longitudinal-field muon spin relaxation ($\ensuremath{\mu}\mathrm{SR}$) measurements. ZF-$\ensuremath{\mu}\mathrm{SR}$ measurement reveals the absence of long-range magnetic ordering down to 70 mK. Interestingly, below 1 K the electronic relaxation rate rises sharply, suggesting the appearance of low-energy quantum spin fluctuations in ${\mathrm{CeCo}}_{2}{\mathrm{Ga}}_{8}$.

International audience; We report on the synthesis and physical properties of the new ternary intermetallic Ce2Rh2Ga. Its formation and dimorphism have been investigated by powder and single crystal X-ray diffractometry, as well as by differential thermal analyses. LT-and HT-Ce2Rh2Ga can be obtained by the chosen respective thermal treatment. The high-temperature form (HT-Ce2Rh2Ga), stable above 864(5)degrees C, is orthorhombic La2Ni3-type [Cmce, oS20, a = 5.851(2) angstrom, b = 9.6184(19) angstrom, c = 7.4871(17) angstrom, V = 421.3(2) angstrom(3)]; the low temperature form (LT-Ce2Rh2Ga), stable below this temperature, is monoclinic Pr2Co2Al-(Ca2Ir2Si-) type [C2/c, mS20, a = 10.0903(6) angstrom, b = 5.6041(3) angstrom, c = 7.8153(4) angstrom, b = 104.995(3)degrees C, V = 426.88(4) angstrom 3]. The magnetic measurements were conducted on two different samples, namely on the LT-Ce2Rh2Ga and the other on the HT-Ce2Rh2Ga sample. The HT-Ce2Rh2Ga compound is found to exhibit a phase transition at 128.5 K. By virtue of the sharp peak anomaly in the temperature dependence of the magnetic susceptibility this phase transition is plausibly of antiferromagnetic origin, but occurs at a remarkably high temperature compared to what is typical for Ce binary and ternary compounds. LT-Ce2Rh2Ga has a ground state of ferromagnetic nature which sets in at a paramagnetic-to-ferromagnetic phase transition at 5.2 K.

The Nd 2 Pt 2 In compound was investigated by means of electrical resistivity ρ ( T ) , heat capacity C p ( T ) , magnetic susceptibility χ ( T ) , magnetization M ( μ 0 H ) and magnetocaloric effect (MCE) measurements. The material orders ferromagnetically at T C = 16 K with a second - order phase transition. In the ordered state, ρ ( T ) can be represented in terms of ferromagnetic (FM) spin - wave dispersion with an energy gap Δ R = 13(1) K in zero field. In concert, the C p ( T ) data in this region can be well described by the same model getting Δ C = 8(1) K in zero field. Above T C , the ρ ( T ) variation is characteristic of electron - phonon interaction in the presence of s − d scattering and crystalline-electric field (CEF). The 4 f - electron specific heat shows a Schottky - type anomaly around 60 K associated with CEF. On the other hand, C p ( T ) data of the non-magnetic homologue La 2 Pt 2 In can be described by the Debye - Einstein model, giving a Debye and Einstein temperature values of 190.3(5) K and 69.8(7) K respectively. At high temperatures, the χ ( T ) data follows the Curie - Weiss relation with an effective magnetic moment μ e f f = 3.61(2) μ B and a Weiss temperature θ p = 17(1) K. The magnitude of MCE was estimated from the isothermal magnetization data to be 6.25 J/(kg.K), 5.01 J/(kg.K), 3.18 J/(kg.K) and 0.47 J/(kg.K) for a field change of 7 T, 5 T, 3 T and 1 T, respectively. The characteristic behaviour of the isothermal magnetic entropy change points to a second - order character of the FM phase transition.

The magnetic ordering in Pr 2 Pt 2 In was investigated by means of magnetization and magnetic susceptibility measurements. The compound was found to order ferromagnetically at T C = 8.8(2) K with a second-order phase transition. The derived critical exponents β = 0.325(2), γ = 1.058(2) and δ = 4.26(4) are close to those expected for a 3D Ising ferromagnet.

PrCo$_2$Ga$_8$ is an orthorhombic quasi-skutterudite type compound which crystallizes in the CaCo$_2$Al$_8$ structure type, with space group $Pbam$ (No. 55). The Pr$^{3+}$ ion has a site symmetry of $C_s$ which predicts a crystal electric field (CEF) level splitting into 9 singlets for $J$ = 4. However, a phase transition at $T_m$ = 1.28~K is observed in electrical resistivity and specific heat results and is reported in this paper. The electrical resistivity shows an upturn below $T_m$ due to the superzone-gap formation. This transition is tuneable in fields and is suppressed to lower temperatures with applied magnetic fields. The electronic specific heat $C_{p}(T)/T$ increases below $T_m$ and reaches a value of 7.37 J/(mol K$^2$) at 0.4~K. The Sommerfeld coefficient, $\gamma$ extracted from the low temperature analysis of $C_\mathrm{4f}(T)/T$ is 637 mJ/(mol K$^2$) indicating a possible mass enhancement of the quasiparticles. The calculated entropy value of 3.05 J/(mol K) is recovered around $T_m$ exhibiting almost 53% of Rln2, where R is the universal gas constant. Magnetic susceptibility results obeys the Curie-Weiss law for data above 100 K with an estimated effective magnetic moment, $\mu_\mathrm{eff}$ = 3.37 $\mu_B$/Pr and Weiss temperature, $\theta_p$ = $-$124 K., Comment: 11 pages, 5 figures, SCES 2017 conference proceedings

We report on X-ray diffraction, electrical transport, heat capacity and magnetocaloric effect measurements of a polycrystalline sample of Pr 2 Pt 2 In . The compound forms in the tetragonal Mo 2 FeB 2 type structure and orders ferromagnetically at T C =9 K. In the ordered state, its thermodynamic and electrical transport properties are dominated by magnon contributions with an energy gap of about 8 K in the spin-wave spectrum. The magnitude of magnetocaloric effect is similar to the values reported for most rare-earth based intermetallics. Characteristic behavior of the isothermal magnetic entropy change maximum points to a second-order character of the ferromagnetic phase transition in the compound studied.

The orthorhombic, space group Cmcm YbFe 2 Al 10 structure type series of compounds are known to form with practically the entire series of rare-earth elements R, but only with the three d − electron elements Fe, Ru, and Os. The Ce-derivatives in particular have been of much interest since the first reports of their highly unusual physical properties. Classified as Kondo insulators, CeRu 2 Al 10 and CeOs 2 Al 10 controversially order magnetically and with uncharacteristically high Neel temperatures of ≃ 28 K. CeFe 2 Al 10 on the other hand shows pronounced semiconducting and Kondo features but remains paramagnetic. As part of our ongoing studies into the rich physics of this class of materials we have succeeded in synthesizing new members of the 1:2:10 stoichiometry involving the chemical element Rh for the first time. CeRh 2 Al 10 is found to crystallize in the tetragonal system with space group I 4 1 / amd . Yb Rh 2 Al 10 on the other hand forms in the serial Cmcm orthorhombic structure type. We discuss important similarities between the two types. At 5.310 A the shortest Ce–Ce distance is, likewise to the situation in CeRu 2 Al 10 and CeOs 2 Al 10 , also well above the Hill limit of 3.40 A. Despite the cage-like structure and large rare-earth separation distances, this study reveals the onset of long-range magnetic ordering in CeRh 2 Al 10 at 3.9 K. The magnetic ordering develops out of an incoherent Kondo state that dominates the electrical resistivity below about 40 K.

The Frank-Kasper cage compound EuV 2 Al 20 crystallizes in the cubic structure with Fd 3 ‾ m space group and exhibits unusual magnetic and transport properties. The system undergoes an antiferromagnetic transition below 5.6 K wherein the Eu 2+ moments are aligned anti-parallel along 〈1 1 1〉 direction and the system exhibits a weak metamagetic transition at the field of 1 T. Arrott plots ( M 2 vs H / M ) show a “S” shaped variation in the low fields below T N and the plausible reason for the occurrence of negative slope is discussed. Isothermal magnetic entropy change is estimated from both magnetization and heat capacity measurements invoking the Maxwell’s thermodynamic relations. Temperature variation of Δ S m showed a weak negative minimum and a sign reversal at the field value of 1 T due to field induced metamagnetic transition. Universal master curve is constructed by rescaling the Δ S m vs T curves in the context of analysing the nature of the magnetic transition.

We present an extended research on characterization of the ground state in a polycrystalline compound Ce2Ir3Al9 using powder x-ray diffraction, magnetic susceptibility χ(T), isothermal magnetization M(B), specific heat Cp(T), electrical resistivity ρ(T), magnetoresistivity ρ(B), thermoelectric power S(T) and thermal conductivity κ(T) measurements, together with a theoretical description of the obtained data to develop a more profound understanding of the physics in this compound. Ce2Ir3Al9 crystallizes in the orthorhombic Y2Co3Ga9-type of structure (space group Cmcm, No. 63, oC56, Z = 4). The χ(T) and Cp(T)/T data reveal the signatures of intermediate valence behaviour on Ce ions with the approximate value of the Kondo temperature TK = 96 K and the Sommerfeld coefficient γ = 31 mJ/mol ⋅ K2. In contrast to the magnetometric and thermodynamic measurements, the transport data (ρ(T) and S(T)) indicate the development of the Kondo lattice state. Accordingly, we expect that for Ce2Ir3Al9 the most likely scenario, which develops in a wide T range is the coexistence and competition of two energy scales of interactions between conduction electrons and 4f spins on Ce ions, located in one unique crystallographic site in the unit cell, in consequence carrying out our system from Ce4+ T e m p . → Ce3+. At higher temperatures, where the Kondo interaction becomes dominant the influence of the crystal electric field effect seems to play an influential role in the ground state of this compound too.

The two new rare-earth pyrocoboltates R 2 Co2O7 (R = Ce, Yb) adopt the layered monoclinic Ca2Nb2O7-type structure with the space group P21 (No. 4). Both compounds have been investigated by DC magnetic susceptibility χ dc ( T ) , AC magnetic susceptibility χ ac ( T ) and isothermal magnetization M ( B ) measurements. The observed effective magnetic moment of Ce2Co2O7 indicates a contribution from the Co sublattice while that of Yb2Co2O7 is mainly from the localized 4 f 13 electronic configuration of Yb3+ ion. A magnetic ordering of the antiferromagnetic-type is observed in Ce2Co2O7 at T N ≃ 34 K. This ordering is accompanied by the opening of a magnetic spectral gap, Δ = 57.7 K ( ~ 5.0 meV) in the spin-wave spectrum and it survives in an external magnetic field of 7 T. In addition to the transition at T N , χ ac ( T ) measurements reveal a dome-like feature centered at ≃ 20 K in high frequency which indicates the presence of possible short-range correlation. In Yb2Co2O7, a magnetic phase transition is observed below T N = 2.94 K, which is suppressed below 1.9 K in an external magnetic field of 3 T. In the low-T region where the crystal electric field effects can be neglected, an effective spin-1/2 state is realized in Yb2Co2O7, with a Lande-g factor of 3.76 which is comparable to values observed from electron spin resonance (ESR) measurements on related systems. In addition, M ( B ) of Yb2Co2O7 shows a metamagnetic-like feature at a critical field of H C ≈ 2.5 T. Signatures from both compounds reveal the presence of strong magnetic frustrations with frustration index f of 9.17 and 15.12 for Ce2Co2O7 and Yb2Co2O7, respectively.

We report the magnetic, electronic and transport properties of the quasi-skutterudite compound Pr3Ir4Ge13 by means of magnetic susceptibility χ(T), electrical resistivity ρ(T), specific heat Cp(T), thermal conductivity κ(T), thermoelectric power S(T) and Hall coefficient RH(T) measurements. Pr3Ir4Ge13 does not show any phase transition down to 1.9 K. Magnetic, and specific measurements show that the system possesses a crystal electric field singlet ground state that is separated from the first excited state by about 37 K. ρ(T) shows a negative temperature coefficient of resistance for the whole temperature range studied and which can be explained in terms of Mott’s impurity band conduction mechanism. RH(T) measurements show that Pr3Ir4Ge13 is a low-carrier density semiconductor and its transport properties indicate a metallic-non metallic cross over behaviour. Large Seebeck coefficient was observed for the entire temperature range of investigation, and the analysis of temperature variation of S and S∕T showed no sign of strong correlation between the Pr 4f2 and conduction electron states near Fermi level.

Dc and ac – magnetic susceptibility (χ), specific heat ( C P ), electrical resistivity (ρ) and magnetoresistance measurements performed on the new polycrystalline compound Gd 2 AgSi 3 , crystallizing in the α – ThSi 2 tetragonal structure, are reported. Two magnetic phase transitions were observed in dc and ac susceptibility, specific heat and resistivity measurements at temperatures T N 1 = 11 K and T N 2 = 20 K, despite a single site occupied by Gd atom, which is an indication of the complex magnetic behavior. Gd 2 AgSi 3 turns out be one of the rare Gd compound in which a minimum is observed in the temperature dependence of resistivity in the paramagnetic state and also negative magnetoresistance over a wide temperature range (above T N 2 ), mimicking the behavior of exotic Gd 2 PdSi 3 , in this ternary family. The isothermal magnetic entropy change, adiabatic temperature change, and refrigerant capacity reach a value of 9.5 J/kg-K, 7.5 K and 302 J/kg, respectively for the change of magnetic field 0-9 T.

We report the magnetotransport and thermodynamic properties of PrPtSi which crystallizes with the noncentrosymmetric LaPtSi-type structure (space group: I41md). Signatures from specific heat and magnetic susceptibility reveal an anomaly at T* ≃ 5.5 K which is attributed to crystal field effects. We find a negative magnetoresistance whose magnitude grows with decreasing temperature, with a value of −17.4% at 1.9 K and in 7 T. Results from the electronic-derived specific heat C4f reveal an upturn in C4f(T)/T at low temperature and traces a −logT dependence, attaining values of 1.1 J/(mol K2) and 3.6 J/(mol K2) at 0.38 K in zero and 4 T, respectively.

We report on dielectric anomalies, competing magnetic interactions and relaxor ferroelectric behaviors of xPMN–PT–(1 – x)NiFe2O4 (x = 0.2 and 0.4) nanocomposites. The crystal structure and surface morphology of the pure and composite nanomaterials were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Phase formation and purity of the NiFe2O4, PMN–PT and the composites were confirmed from XRD measurements. Uniformly distributed nanoparticles and nanowires and the presence of Ni, Fe, O, Pb, Nb, Mg, and Ti in NiFe2O4 and PMN–PT are confirmed from FESEM and energy dispersive X-ray (EDX) measurements. Structural disordering due to phase transition around 453 K in both composites was examined from temperature variation Raman studies. Magnetization measurements at room temperature and at 40 K, zero field cooled (ZFC) and field cooled (FC) magnetization measurements for both composites were carried out from 2 to 350 K. Competing magnetic interacti...

A new member of the RET 2 Al 10 family was synthesized and its crystal structure was determined from single crystal X-ray diffraction. The first aluminide with rhodium adopts a new structure type of 1:2:10 stoichiometry. CeRh 2 Al 10 crystallizes in the tetragonal space group I 4 1 / amd with cell parameters a = 8.9284(11) A and c = 21.769(3) A and is a substitution variant of CePd 3 Al 9 compound. The mutual arrangement of Rh and Al neighbors within the 20-vertex Ce polyhedron differs in comparison with that of the CeRu 2 Al 10 structure. This leads to the different packing of Ce polyhedra in the unit cell. In CeRh 2 Al 10 , zig-zag chains of the shortest Ce Ce contacts extend in the two mutually perpendicular directions – along the a -axis and along the b -axis. In contrast, in CeRu 2 Al 10 , zig-zag chains of the shortest Ce Ce contacts run in one direction – along the c -axis. We illustrate using key physical properties how the variation in crystal structure produces physical properties in CeRh 2 Al 10 that differ strikingly from the situation in CeRu 2 Al 10 .

Graphene oxide potentially used as an intermediary in the production of single layer or few-layer graphene sheets. To achieve this, an oxidization and reduction process is used to developed single/few-layers and separate them without changing their structure. Graphene oxide has potential applications in many areas, e.g., electronics, magnetic, catalysis, and energy storage, because of its high charge-carrier mobility and high specific surface area. This study investigates the electronic and magnetic properties of graphene oxide (GO), and nitrogen functionalised graphene oxide (GO-Nx). GO is prepared using chemical process and hence functionalized with nitrogen precursors. GO and GO-Nx are characterised using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and Raman spectroscopy. Nitrogen functionalized GO become more graphitic in structure as observed from Raman spectroscopy and N 1s XPS spectrum that turn into higher magnetization observed from M-H hysteresis loops. The electronic density of states of GO-Nx is significantly higher than as compared to the GO as a result the magnetic properties also enhanced on GO-Nx. Our experimental results thus provide new evidences to control the magnetic and electronic properties of GO and GO-Nx for different electronic and magnetic device applications.

We report on structural, spin glass behaviour and competing magnetic interactions in xNiFe2O4 - (1-x)BaTiO3 (x = 0.2 and 0.3) nanocomposites prepared by sol-gel method. The structure and surface morphology of the NiFe2O4-BaTiO3 composites were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD measurements of composite materials show the presence of both NiFe2O4 and BaTiO3 phases. FESEM and energy dispersive X-ray (EDX) measurements indicate uniformly distributed nano size particles and presence of Ni, Fe, O, Ba and Ti elements respectively. Temperature variation Raman spectra indicates large structural disordering (Peak broadening and shift) around 395 K due to the structural transformation of BaTiO3. Magnetization, zero field cooled (ZFC) and field cooled (FC) measurements were carried out from 2 K to 320 K for both composites. ZFC and FC measurements reveal the spin glass and Superparamagnetism like behaviour along with competing magnetic interaction in both composites. Saturation magnetization value is seen to increase from 6.7 to 10 emu/g with increasing Ni ferrite composition from x = 0.2 to x = 0.3. Distribution function associated with magnetocrystalline anisotropy energy barrier exhibits broad peaks due to the random distribution of spins associated with different particle size in the x = 0.3 composition.

The alloys Ce 8 Pd 24 ( Al 1 − x Sn x ) with 0 ≤ x ≤ 1 were studied by means of electrical resistivity, thermal conductivity, thermoelectric power, magnetic susceptibility and magnetization measurements. In the entire composition range, an antiferromagnetic (AFM) long-range ordering has been established at low temperatures, with the Neel temperature increasing linearly from T N = 4.3 K for Ce 8 Pd 24 Al to T N = 7 K for Ce 8 Pd 24 Sn . Below T N , the electrical resistivity is dominated by scattering conduction electrons on spin-wave excitations. In the paramagnetic state, the electrical transport in the alloys with 0 ≤ x ≤ 0.7 reveals both coherent Kondo lattice scattering and crystal-electric field (CEF) effect, while that in the alloys with x ≥ 0.8 appears governed by CEF only. Above T N , all the alloys exhibit well localized magnetic behavior due to trivalent Ce ions. At high temperatures, the thermoelectric power can be interpreted in terms of a phenomenological resonance model giving an estimate of the CEF effect. The thermoelectric figure of merit of Al-rich alloys is small compared to those of commercial thermoelectric materials.

The superconducting phase transition at $$T_\mathrm{c} = 2.3$$ K was observed for the electrical resistivity $$\rho ({T})$$ and magnetic susceptibility $$\chi (T)$$ measurements in the ternary compound La $$_{5}\hbox {Ni}_{2}\hbox {Si}_{3}$$ that crystallizes in the hexagonal-type structure. Although a single-phase character with the nominal stoichiometry of the synthesized sample was confirmed, a small trace of the La–Ni phase was found, being probably responsible for the superconducting behaviour in the investigated compound. The magnetization loop recorded at $${T} = 0.5$$ K resembles a star-like shape which indicates that the density of the critical current can be strongly suppressed by a magnetic field. The low- $$T _{\rho }(T)$$ and specific heat $${C}_\mathrm{p}({T})$$ data in the normal state reveal simple metallic behaviour. No clear evidence of a phase transition to any long- or short-range order was found for $$C_\mathrm{p}(T)$$ measurements in the T-range of 0.4–300 K.

The interplay of antiferromagnetic (AFM) and Kondo effect in Ce 8 Pd 24 Al with the dilution of Ce with La is investigated by means of electrical and thermal transport and magnetic properties measurements. X - ray diffraction studies confirm a cubic AuCu 3 - type crystal structure with space group Pm 3 ¯ m for all compositions in the alloy series ( Ce 1 − x La x ) 8 Pd 24 Al ( 0 ≤ x ≤ 1 ) . Electrical resistivity, ρ ( T ) results show evolution from coherent Kondo lattice scattering with a well defined Kondo peak at Tmax to incoherent single-ion Kondo scattering with increasing La content x. Magnetoresistivity MR measurements on Ce dilute alloys are negative and analyzed based on the calculations by Schlottmann for the Bethe - ansatz in the framework of the Coqblin - Schrieffer model and yield values of the Kondo temperature TK and the effective moment of the Kondo ion μK. The decrease of Tmax and TK is described by the compressible Kondo lattice model. The thermoelectric power, S(T) measurements are interpreted within the phenomenological resonance model. The Lorentz number, L / L 0 increases rapidly on cooling the samples and reaches a maximum value around 6 K. The magnetic susceptibility, χ ( T ) data at high temperature follow the Curie - Weiss behaviour and yield effective magnetic moments, μeff values across the series close to the value of 2.54 μB expected for the free Ce 3 + - ion. The low temperature χ ( T ) shows an AFM anomaly associated with a Neel temperature TN for alloys in the range 0 ≤ x ≤ 0.2 . No metamagnetic transition was observed from the magnetization results, M ( μ 0 H ) .

In this article, we report the modification of the electronic and magnetic properties of few-layered graphene (FLG) nanoflakes by nitrogen functionalization carried out using radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD) and electron cyclotron resonance (ECR) plasma processes. Even though the rf-PECVD N2 treatment led to higher N-doping levels in the FLG (4.06 atomic %) as compared to the ECR process (2.18 atomic %), the ferromagnetic behavior of the ECR FLG (118.62 × 10–4 emu/g) was significantly higher than that of the rf-PECVD FLG (0.39 × 10–4 emu/g) and pristine graphene (3.47 × 10–4 emu/g). Although both plasma processes introduce electron-donating N atoms into the graphene structure, distinct dominant nitrogen bonding configurations (pyridinic, pyrrolic) were observed for the two FLG types. Whereas the ECR plasma introduced more sp2-type nitrogen moieties, the rf-PECVD process led to the formation of sp3-coordinated nitrogen functionalities, as confirmed through Raman measurem...

We report a detailed study of the magnetization modulus as a function of temperature and applied magnetic field under varying angle in Sr$_{4}$Ru$_{3}$O$_{10}$ close to the metamagnetic transition at $H_{c}\backsimeq 2.5\,$T for $H \perp c$. We confirm that the double-feature at $H_{c}$ is robust without further splitting for temperatures below 1.8 K down to 0.48 K. The metamagnetism in Sr$_{4}$Ru$_{3}$O$_{10}$ is accompanied by a reduction of the magnetic moment in the plane of rotation and large field-hysteretic behavior. The double anomaly shifts to higher fields by rotating the field from $H\,\perp \,c$ to $H\,\parallel\,c$. We compare our experimental findings with numerical simulations based on spin reorientation models caused by intrinsic magnetocrystalline anisotropy and Zeeman effect. Crystal anisotropy is able to explain a metamagnetic transition in the ferromagnetic ordered system Sr$_{4}$Ru$_{3}$O$_{10}$, but a Dzyaloshinskii-Moriya term is crucial to account for a reduction of the magnetic moment as discovered in the experiments., Comment: 7 pages, 8 figures

The effects of substituting moment-bearing Tb in CePt 2 Si 2 are reported through X-ray diffraction (XRD), electrical resistivity ( ρ ( T ) ), magnetic susceptibility, ( χ ( T ) ), and magnetization, ( σ ( μ 0 H ) ) measurements. XRD results for all compositions of ( Ce 1 − x Tb x ) Pt 2 Si 2 system indicate a tetragonal CaBe 2 Ge 2 - type structure with space group P 4 / n m m . ρ ( T ) results indicate a rapid evolution from a coherent Kondo lattice for the CePt 2 Si 2 parent compound to incoherent single-ion Kondo behaviour with substitution of Tb for Ce. However, between 90% and 100% of Tb content, the ( Ce 1 − x Tb x ) Pt 2 Si 2 system reverts back to stable local - moment, normal metal behaviour. χ ( T ) data at higher temperature follow the Curie - Weiss relation for all alloy compositions and give effective moment values μ e f f which increase gradually from the expected values of 2.54 μ B for the Ce 3 + - ion to 9.72 μ B for the Tb 3 + - ion. At low temperature χ ( T ) data exhibit antiferromagnetism at the N e ′ el temperature T N in the concentration range 0.7 ≤ x ≤ 1 . Below T N the zero-field-cooled and field-cooled susceptibility bifurcate in a 0.1 T field, suggesting an inhomogeneous magnetic ground state as a result of spin glass - like state for compositions in the range 0.6 ≤ x ≤ 1 . No evidence of metamagnetic behaviour was observed from σ ( μ 0 H ) data for all compositions.

We present magnetization measurements on Sr 4 Ru 3 O 10 as a function of temperature and magnetic field applied perpendicular to the magnetic easy c-axis inside the ferromagnetic phase. Peculiar metamagnetism evolves in Sr 4 Ru 3 O 10 below the ferromagnetic transition T C as a double step in the magnetization at two critical fields H c 1 and H c 2 . We map the H − T phase diagram with special focus on the temperature range 50 K ≤ T ≤ T C . We find that the critical field H c 1 ( T ) connects the field and temperature axes of the phase diagram, whereas the H c 2 boundary starts at 2.8 T for the lowest temperatures and ends in a critical endpoint at (1 T; 80 K). We conclude from the temperature dependence of the ratio Hc 1 Hc 2 ( T ) that the double metamagnetic transition is an intrinsic effect of the material and it is not caused by sample stacking faults such as twinning or partial in-plane rotation between layers.

High-quality single crystals of NaYbSe$_2$, which resembles a perfect triangular-lattice antiferromagnet without the intrinsic disorder, are investigated by magnetization and specific heat, as well as the local probe techniques nuclear magnetic resonance (NMR) and electron spin resonance (ESR). The low-field measurements confirm the absence of any spin freezing or long-range magnetic order down to 50~mK, which suggests a quantum spin liquid ground (QSL) state with gapless excitations. The instability of the QSL state is observed upon applying magnetic fields. For the $H\bot c$ direction, a field-induced magnetic phase transition is observed above 2~T from the $C_{\rm p}(T)$ data, agreeing with a clear $\frac{M_s}{3}$ plateau of $M(H)$, which is associated with an up-up-down (uud) spin arrangement. For the $H\|c$ direction, a field-induced transition could be evidenced at a much higher field range (9 - 21~T). The $^{23}$Na NMR measurements provide microscopic evidence for field-induced ordering for both directions. A reentrant behavior of $T_{\rm N}$, originating from the thermal and quantum spin fluctuations, is observed for both directions. The anisotropic exchange interactions $J_{\perp}\simeq$ 4.7~K and $J_z\simeq$2.33~K are extracted from the modified bond-dependent XXZ model for the spin-$\frac{1}{2}$ triangular-lattice antiferromagnet. The absence of magnetic long-range order at zero fields is assigned to the effect of strong bond-frustration, arising from the complex spin-orbit entangled $4f$ ground state. Finally, we derive the highly anisotropic magnetic phase diagram, which is discussed in comparison with the existing theoretical models for spin-$\frac{1}{2}$ triangular-lattice antiferromagnets., 6 Figures

Features of low-dimensional magnetism resulting from a square-net arrangement of Co atoms in trirutile ${\mathrm{CoTa}}_{2}{\mathrm{O}}_{6}$ are studied in the present work by means of density functional theory and are compared with the experimental results of specific heat and neutron diffraction. The small total energy differences between the ferromagnetic (FM) and antiferromagnetic (AFM) configuration of ${\mathrm{CoTa}}_{2}{\mathrm{O}}_{6}$ shows that competing magnetic ground states exist, with the possibility of transition from FM to AFM phase at low temperature. Our calculation further suggests the semiconducting behavior for ${\mathrm{CoTa}}_{2}{\mathrm{O}}_{6}$ with a band gap of $\ensuremath{\sim}0.41$ eV. The calculated magnetic anisotropy energy is $\ensuremath{\sim}2.5$ meV with its easy axis along the [100] (in-plane) direction. Studying the evolution of magnetism in ${\mathrm{Co}}_{1\ensuremath{-}x}{\mathrm{Mg}}_{x}{\mathrm{Ta}}_{2}{\mathrm{O}}_{6}$ ($x=0$, 0.1, 0.3, 0.5, 0.7, and 1), it is found that the sharp AFM transition exhibited by ${\mathrm{CoTa}}_{2}{\mathrm{O}}_{6}$ at ${T}_{N}=6.2$ K in its heat capacity vanishes with Mg dilution, indicating the obvious effect of weakening the superexchange pathways of Co. The current specific heat study reveals the robust nature of ${T}_{N}$ for ${\mathrm{CoTa}}_{2}{\mathrm{O}}_{6}$ in applied magnetic fields. Clear indication of short-range magnetism is obtained from the magnetic entropy, however, diffuse components are absent in neutron diffraction data. At ${T}_{N}, {\mathrm{CoTa}}_{2}{\mathrm{O}}_{6}$ enters a long-range ordered magnetic state which can be described using a propagation vector, ($\frac{1}{4}\frac{1}{4}0$). Upon Mg dilution at $x\ensuremath{\ge}0.1$, the long-range ordered magnetism is destroyed. The present results should motivate an investigation of magnetic excitations in this low-dimensional anisotropic magnet.

The cubic intermetallic compound Sm 3Co 4Ge 13 (space group P m 3 &macr, n ) possesses a cage-like structure composed of Ge and displays an antiferromagnetic transition at T N &asymp, 6 K in magnetization, M ( T ) , specific heat, C p ( T ) and in thermal conductivity, &kappa, ( T ). The magnetic transition at T N is observed to be robust against applied magnetic fields up to 9 T. From the analysis of specific heat, a Sommerfeld coefficient &gamma, = 80(2) mJ/mol-Sm K 2 is estimated. The magnetic entropy released at T N is estimated as lower than that of a doublet, R ln(2). A positive Seebeck coefficient is observed for the thermopower, S ( T ) . Photoemission spectroscopy reveals distinct electronic character of the near-E F valence band states arising out of Co( 3 d)-Sm( 4 f) hybridization and Sm( 4 f) electron correlation. The unusual field-independent features in magnetization, specific heat and electrical transport is an indication of the significant correlation between f and d wave functions.

The influence of Y- and La-substitution for Ce on the competing Kondo effect and magnetic ordering, as well as on spin dynamics in the Kondo semiconductor CeRu2Al10 have been investigated by means of thermal, electronic, and magnetic properties. The parent compound CeRu2Al10 is known to be a controversial antiferromagnet with high magnetic ordering temperature T 0 = 27 K. A small negative chemical pressure caused by La-doping results rapid suppression of T 0 and spin gap energy Δ m , compared to a small positive pressure caused by Y-doping. Upon Y- and La-doping, the electrical resistivity ρ(T) illustrates the evolution from dense Kondo semiconductor to incoherent single-ion Kondo behaviour, and hence weakens the c–f hybridization and thus lowers the Kondo temperature. The 5% Y- and La-doped compounds show enormous enhancement in the thermoelectric power and complex behaviour in the Hall resistivity below T 0 due to an abrupt change in charge carrier mobility with temperature. The magnetic contribution to electrical resistivity ρ mag(T) (≳50% La) and specific heat C P(T)/T (≳70% La) evidence non-Fermi-liquid behaviour at low temperature in the La-doped system, due to interplay of atomic disorder with spin-fluctuation. Application of magnetic field suppresses the spin-fluctuation in C P(T)/T and eventually emerges to Fermi-liquid state in the 95% La-doped compound in 9 T. The magnetic phase diagram illustrates that the strength of the Kondo interaction in the doped systems are primarily controlled by the effect of volume change as described by the compressible Kondo lattice model. We ascribe the fascinating observation of T K ≃ 4T 0 to anisotropy in the single-ion crystal electric field in the presence of strong anisotropic c–f hybridization.

Ternary stannides CePd 3 Sn and LaPd 3 Sn were synthesized by arc melting the elements. Their crystal structures determined at room temperature revealed a new structure type: sp. gr. Cmcm , Z = 4, a = 4.5160(18) A, b = 15.878(8) A, c = 5.396(3) A for CePd 3 Sn and a = 4.5187(10) A, b = 15.961(5) A, c = 5.451(2) A for LaPd 3 Sn. The new type of structure can be presented as built of two types of slabs stacked along the b-axis – CePdSn slab of PbFCl-type and palladium corrugated slab. CePd 3 Sn and LaPd 3 Sn undergo reversible crystal structure phase transition at 141 K and 260 K, respectively. The temperature hysteretic behavior through the transition is tracked with electrical resistivity and magnetic susceptibility. Single-crystal X-ray diffraction data at 120 K showed that the low-temperature (LT) polymorph of CePd 3 Sn crystallizes in the monoclinic structure type, with C 2/ m space group, Z = 16 and lattice parameters a = 10.8314(7) A, b = 9.0474(5) A, c = 15.8725(12) A, β = 91.325(6)°. LT−CePd 3 Sn is found to order at low temperature into a putative antiferromagnetic spin structure below 1 K.

Measurements are presented on the resistivity ρ ( T ), magnetoresistivity MR, dc susceptibility χ ( T ) and magnetization σ ( μ 0 H ), of the alloy series Ce 8 Pd 24 Al x with 0.1 ≤ x ≤ 2. Rietveld analysis of the X-ray diffraction (XRD) data indicates that Ce 8 Pd 24 Al crystallizes in the cubic structure with space group P m 3 ¯ m (No. 221). The crystal structure of this compound is composed of 8 cubes of CePd 3 in which the Al atoms occupy the centres of only certain octahedrons of Pd atoms. The CAILS - Pawley (cell and intensity least square) analysis of XRD data of all compositions show that the cubic structure of the parent compound CePd 3 is retained. The XRD analysis indicate a linear increase in the cubic unit cell volume up to x = 1, followed by a curvature for larger Al concentrations and a tendency towards saturation on approaching x = 2. Measurements in the Al-poor alloy in the temperature range 4.2–300 K indicate an evolution from the intermediate valence state of Ce 8 Pd 24 to Kondo behaviour with increased Al concentration. MR measurements on selected alloys are interpreted within the single-ion Bethe ansatz description and values of the Kondo temperature are calculated. χ ( T ) follows a Curie-Weiss behaviour with high-temperature effective moment values slightly reduced from the expected value of 2.54 μ B of the free Ce 3+ -ion. The paramagnetic Weiss constant temperature − θ p decreases rapidly with increasing Al content x , in line with the evolution from intermediate valence state to Kondo state. Low-temperature χ ( T ) data indicate antiferromagnetic ordering for the concentration range of 0.96 ≤ x ≤ 2. A Kondo and magnetic phase diagram for the Ce 8 Pd 24 Al x system is presented.

CoSn x Fe2−x O4 (x = 0, 0.1, 0.5, and 1.0) nanoparticles have been synthesized and characterized by XRD, FTIR, TEM, SEM, Mossbauer spectroscopy, and SQUID measurements. XRD data confirm single-phase cubic spinel structure formation and particle size between 10 and 23 nm. The Mossbauer spectra recorded at about 300 K is indicative of ordered magnetic spin phase. Magnetization and Mossbauer data show the superparamagnetic nature of the compound CoSn x Fe2−x O4 (x = 0.5). The evolution of the properties as a function of x is discussed on the basis of particle size and Sn concentration. A strong correlation between coercive fields and crystallite sizes measured at room temperature is observed.

We report the electrical and thermal transport properties of NdCu 4 Au and GdCu 4 Au compounds, crystallizing in the cubic MgCu 4 Sn - type crystal structure, with space group F 4 ¯ 3 m (no. 216).These properties are reported through measurements of electrical resistivity, ρ ( T ) , thermoelectric power, S ( T ) and thermal conductivity, λ ( T ) . ρ ( T ) and S ( T ) data indicate an antiferromagnetic (AFM)-like anomaly associated with a N e el temperature T N =3.9 K and 10.9 K for NdCu 4 Au and GdCu 4 Au compounds, respectively. ρ ( T ) data for both compounds shows a sudden drop at T N . Above T N , ρ ( T ) results are characteristic of an electron–phonon interaction in the presence of s − d scattering. Application of magnetic field slightly suppresses T N value in GdCu 4 Au compound from T N =10.9 K in a field of 0 T to 10.1 K in a field of 6 T. S ( T ) data at low temperatures for both compounds shows a minimum at T N . Critical analysis of S ( T ) in terms of the phenomenological resonance model yield the positions ( E f ) and bandwidths ( W f ) of the 4 f - band in both compounds: E f =3.81(6)K, W f =329(58) K for the Nd compound and E f =18.2(4) K, W f =306(5) K for the Gd compound. λ ( T ) for both compounds decreases linearly upon cooling from room temperature. The reduced Lorentz number L / L 0 deviates from the Wiedmann–Franz at low temperature with a strong increase in L / L 0 upon cooling the samples from room temperature.

The robust field-insensitive heavy fermion features in Sm3 Ru4 Ge13 and the magnetic phase transition at TN ≈ 5 K are studied using magnetization M(T), specific heat Cp(T), resistivity ρ(T) and thermal conductivity κT(T). The average crystal structure of Sm3 Ru4 Ge13 conforms to the cubic space group P m 3 ¯ n however, signatures of subtle structural distortions are obtained from the x ray data. The magnetic susceptibility, χ(T), follows a modified Curie–Weiss law indicating the presence of crystal fields of Sm3+ and the significance of van Vleck terms. No sign of ferromagnetism is observed in M(H) of Sm3 Ru4 Ge13 which yields only 0.025 μB/f.u.-Sm at 2 K, 7 T. The Sommerfeld coefficient, γ≈ 220 mJ/mol-Sm K2, estimated from the analysis of low temperature specific heat suggests the formation of heavy quasi particles at low temperature. Though a lnT dependence of ρ(T) is observed till 60 K, the resistivity behavior is accounted for by assuming a two-band model for activated behavior of charge carriers. The field scans of resistivity, ρ(H), below TN display significant nonlinearity while those above the TN are more metal-like. Low values of thermal conductivity, κT(T), are observed in Sm3 Ru4 Ge13 however, displaying an anomaly at TN which signifies magnetoelastic coupling. A fairly high value of Seebeck coefficient, S ≈ 40 μV/K is observed at 300 K. We identify Sm3 Ru4 Ge13 as a low charge carrier density system with unusual field-insensitive heavy fermion features very similar to the filled skutterudites.

We report the synthesis of the antiferromagnet cubic-type structure NdCu4Au derived by substituting Au for Cu in the parent binary NdCu5 compound. The room temperature X-ray diffraction analysis indicates a cubic MgCu4Sn-type structure with space group F 4 ¯ 3 m (No. 216) for the NdCu4Au compound. The thermodynamic properties of NdCu4Au have been probed by magnetic susceptibility, χ ( T ) , magnetization, M ( μ 0 H ) , and specific heat, Cp(T), measured down to 1.8 K. The low temperature χ ( T ) data shows probably an antiferromagnetic (AFM)-like anomaly associated with a Neel temperature TN=3.9 K. In the paramagnetic region, χ ( T ) data follows the modified Curie–Weiss law with an effective magnetic moment μ eff = 3.547 ( 5 ) μ B and Weiss temperature θ p = − 10.19 ( 8 ) K . The value for μeff is close to the value of 3.62 μB expected for the Nd3+-ion. No evidence of metamagnetic transition was observed from the isothermal M ( μ 0 H ) results. Cp(T) data confirm the AFM phase transition at TN=3.5 K close to the value of 3.9 K observed in χ ( T ) . The 4f-electron specific heat shows a Schottky-type anomaly around 20 K associated with crystalline-electric-field (CEF), with energy splitting Δ1=62(5) K and Δ2=109(9) K of the Nd3+ (J=9/2) multiplet, that are associated with the first and second excited state of Nd3+-ion. From the results of the 4f-electron magnetic entropy, it is speculated that the CEF ground state of Nd3+ (J=9/2) ions is the Γ6 doublet for NdCu4Au.

Targeted delivery of carmustine (BCNU), an efficient brain tumor therapeutic, has been challenged with bioavailability issues due to the Blood Brain Barrier (BBB). The currently effective delivery approach is by implants at the site of the tumor, but this is highly invasive. The intranasal route, which is non-invasive and bypasses the BBB, may be alternative route for delivering BCNU to the brain. In this work, polyvinyl alcohol/polyethyleneimine/fIuorecein isothiocyanate complex (Polyplex) coated iron-oxide nanoparticles (Magnetite) were synthesized employing co-precipitation, epoxidation and EDC/NHS coupling reactions. The Polyplex coated magnetite (Nano-co-Plex) was loaded with BCNU for potential magnetically targeted delivery to the brain following intranasal administration. The Nano-co-Plex was characterized employing Thermogravimetric analysis (TGA), Superconducting Quantum Interference Device (SQUID) magnetometry, Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), X-ray Diffractometry (XRD), Transmission Electron Microscopy (TEM) and Zetasize analysis. Results revealed superparamagnetic hexagonally shaped "core-shell" nanoparticles with cell labeling attributes, of size ranging between 30-50 nm, and a zeta potential value of + 32 ± 2 mV. The Nano-co-Plex synthesized was found to possess high degree of crystallinity with 32% Polyplex coating. The loading and release studies indicated a time-dependent loading with maximum loading capacity of 176.82 μg BCNU/mg of the carrier and maximum release of 75.8% of the loaded BCNU. Cytotoxicity of the BCNU-loaded Nano-co-Plex displayed superiority over the conventional BCNU towards human glioblastoma (HG) cells. Cell studies revealed enhanced uptake and internalization of BCNU-loaded Nano-co-plex in HG cells in the presence of an external magnetic field. These Nano-co-Plexes may be ideal as an intranasal magnetic drug targeting device for BCNU delivery.

Saturation magnetization (Ms) of pristine bi-/tri-layered graphene (denoted as – FLG) is enhanced by over four (4) and thirty-four (34) times to 13.94 × 10−4 and 118.62 × 10−4 emu g−1, respectively, as compared to pristine FLGs (Ms of 3.47 × 10−4 emu g−1), via plasma-based-hydrogenation (known as graphone) and nitrogenation (known as N-graphene) reactions, respectively. However, upon organo-silane treatment on FLG (known as siliphene), the saturation magnetization is reduced by over thirty (30) times to 0.11 × 10−4 emu g−1, as compared to pristine FLG. Synchrotron based X-ray absorption near edge structure spectroscopy measurements have been carried out to investigate the electronic structure and the underlying mechanism responsible for the variation of magnetic properties. For graphone, the free spin available via the conversion of the sp2 → sp3 hybridized structure and the possibility of unpaired electrons from induced defects are the likely mechanism for ferromagnetic ordering. During nitrogenation, the Fermi level of FLGs is shifted upwards due to the formation of a graphitic like extra π-electron that makes the structure electron-rich, thereby, enhancing the magnetic coupling between magnetic moments. On the other hand, during the formation of siliphene, substitution of the C-atom in FLG by a Si-atom occurs and relaxes out the graphene plane to form Si–C tetrahedral sp3-bonding with a non-magnetic atomic arrangement showing no spin polarization phenomena and thereby reducing the magnetization. Thus, plasma functionalization offers a simple yet facile route to control the magnetic properties of the graphene systems and has potential implications for spintronic applications.

We report the crystal structure as well as the magnetic, electronic and transport properties of PrCu2Au3 which crystallizes in the MgCu4Sn-type structure with the cubic space group F 4 ¯ 3 m (No. 216). In this structure, the Pr3+ ion sits on a lattice site with the cubic T d symmetry which dictates the crystal electric field (CEF) splitting of the Hund’s 3H4 ground multiplet into four levels. The sample has been investigated by measurements of temperature dependences of specific heat, C p ( T ) , electrical resistivity, ρ ( T ) , magnetic susceptibility, χ ( T ) , isothermal magnetization, M ( B , T ) , thermal conductivity, κ T ( T ) and thermoelectric power, S ( T ) . χ ( T ) follows a Curie-Weiss behavior above 100 K with an effective magnetic moment, μ eff = 3.3 μ B /Pr which is comparable to a calculated value of 3.58 μ B /Pr for a free Pr3+ ion and a Weiss temperature, θ CW = 15.70 K indicating a dominant ferromagnetic interaction. From the analysis of M ( B , T ) and the 4f-electron derived specific heat ( C 4 f ( T ) ) results, the CEF ground state is a Γ 5 magnetic triplet and the CEF energy scheme is presented. The Sommerfeld coefficient, γ estimated from the low-temperature C 4 f ( T ) is 304 mJ/(mol K2) indicating a mass enhancement of the conduction electrons at low temperatures. Further analysis of the heavy fermion properties based on the Sommerfeld-Wilson ratio supports the formation of a heavy fermion state in PrCu2Au3. However, the absence of an enhancement in S / T at low temperatures possibly suggests a weak correlation between the conduction electrons and the 4 f -electrons at the Fermi energy. The thermal transport properties suggest that PrCu2Au3 is likely a compensated metal.

Magnetic phase transitions in two Mg 2 Ni 3 Si -type of Gd2Rh3Ge and Er2Rh3Ge compounds (space group R 3 ‾ m , hR18) belonging to rhombohedral Laves phases are studied in this paper. Structural investigations using X-ray diffraction and subsequent Rietveld analysis confirm the rhombohedral R 3 ‾ m Laves phase for both compounds. Magnetization as a function of temperature, M ( T ) , identifies the ferromagnetic transition temperature in both samples with T C = 64 K and 20 K for Gd2Rh3Ge and Er2Rh3Ge respectively which is supported by the specific heat, C p ( T ) . Arrott plots, universal scaling curves by normalizing magnetic entropy changes ( Δ S m ) and field dependent Δ S m revealed that both compounds undergo second order ferromagnetic phase transitions at T C . Significant magnetocaloric effect (MCE) is observed for both compounds, attaining a value of 12 J kg−1 K−1 at T = 64 K, H = 7 T for Gd2Rh3Ge and 11 J kg−1 K−1 at T = 20 K, H = 7 T for Er2Rh3Ge. The adiabatic temperature change is 5.9 K for Gd2Rh3Ge and 10.5 K for Er2Rh3Ge for H = 7 T.

In the last few decades there has been growing interest in studying Mott insulators due to their ability to host novel quantum phenomena when the system is perturbed by various stimuli. Recently the antiferromagnetic Mott insulator Ca2RuO4 has received considerable attention due to superconductivity and metal-insulator transition induced by pressure and electric field respectively. Here we report the details of the synthesis of a novel systems made by Ca2RuO4 and Ru metal inclusions. Samples with lamellae, rods and globules of Ru embedded in Ca2RuO4 single crystals were successfully synthesized by floating zone technique with an excess of Ru in the starting material. The morphology and structural studies revealed a randomly orientated distribution of the shining Ru inclusions with an average size of few microns. Magnetic and electrical properties showed a behavior similar to the one observed in single crystals with the only Ca2RuO4 phase. We also measured the current-voltage characteristics of the whole Ca2RuO4–Ru system and of a single Ru rod by electric micro-contacts estimating the room temperature resistivity of the Ru embedded inclusions. This study shows that physical properties of Ca2RuO4–Ru metal system are related to the properties of the constituent phases, similarly to the case of Sr2RuO4–Ru metal.

Here we report the magnetic, electronic and thermal transport properties of the heavy-fermion semimetal Pr3Os4Ge13 with a cage-like structure by means of magnetic susceptibility, χ(T), isothermal magnetization, M(B, T), electrical resistivity, ρ(B, T), Hall coefficient, R H(T), specific heat, C p(T), thermal conductivity, κ(T) and thermoelectric power, S(T). ρ(T) and R H(T) show semimetallic features in a manner that mimics a thermal activated behaviour with an activation energy, Δ/k B = 6.5 K indicating the opening of a small energy gap in the material. At low temperatures, a Sommerfeld coefficient, γ = 128 mJ (mol-1 K-2) observed indicates a mass enhancement of the quasiparticles at low temperatures which bears witness to a heavy fermion state in Pr3Os4Ge13. A Wilson-Sommerfeld ratio, W R and the dimensionless ratio, S/γT of 1.01 and 0.62 ± 0.018 observed, respectively, are in good agreement with the Fermi liquid scenario. S(T) and R H(T) reveal hole dominated transport (p-type material) with a relatively large room temperature value of S(T) = 32.85 ± 0.98 μV K-1. A room temperature low value of κ(T) = 1.61 W K-1 m-1 leads to a thermoelectric figure of merit, ZT = 0.03 ± 0.001 which is comparable to values achieved in several clathrates around the same temperature. Features from S(T) and ρ(T) favour the realization of a higher ZT value at elevated temperatures.

The critical behavior of a new ternary intermetallic compound Gd 2 Rh 3 Ge has been investigated around the second order ferromagnetic transition temperature ( T C ). The field dependence of magnetic entropy changes and isothermal magnetization at critical temperature were used to study critical behavior in Gd 2 Rh 3 Ge . The exponents β = 0.299(2) and γ = 1.042(1) were evaluated from the modified Arrott-plot method, while β = 0.308(1) and γ = 0.982(2) were estimated through the Kouvel-Fisher method. The reliability of the obtained critical exponents were examined by using the universal scaling hypothesis. These estimated values for the critical exponents indicate that the ferromagnetic compound Gd 2 Rh 3 Ge has long-range interactions between spins, which decays with distance (r) as J(r) ∼ r - ( σ + d ) with σ = 1.91.

Critical behavior in the Nd2Pt2In compound around the ferromagnetic phase transition at TC was investigated based on the magnetocaloric effect (MCE). The critical exponent values β = 0.42(6), γ = 1.25(2) and δ = 4.00(2) obtained from the magnetic entropy change at TC and the critical magnetization isotherm, M(μ0H, TC), indicated that the magnetic interactions in this compound follow two different universality classes below and above TC, which can be described in terms of the 3D-Heisenberg and 3D-Ising models, respectively. The studies by means of the conventional method using different techniques gave values of the critical exponents that are in close agreement with those derived from the MCE analysis and also confirmed two different behaviors in the ferromagnetic and paramagnetic states.

We report on the low-temperature physical properties of RE 8 Pd 24 Ga (RE = Gd, Tb and Dy) compounds studied by means of thermodynamic and electronic transport measurements. The three compounds exhibit a putative antiferromagnetic ordering. In the paramagnetic region, their magnetic susceptibility follows the Curie-Weiss relation with effective magnetic moments close to those expected for the respective RE 3 + ions. Gd 8 Pd 24 Ga and Dy 8 Pd 24 Ga undergo another magnetic phase transitions in the ordered state. In fairly small magnetic fields, the magnetization of Tb 8 Pd 24 Ga and Dy 8 Pd 24 Ga reveals a metamagnetic-like transition that bears a first-order character. All three compounds studied exhibit magnetocaloric effect of the magnitude similar to those reported for materials applicable as magnetic refrigerants.

The physical properties of the very-heavy-fermion compound ${\mathrm{YbCu}}_{4}\mathrm{Ni}$ were characterized through structural, magnetic, thermal, and transport studies along nearly four decades of temperature ranging between 50 mK and 300 K. At high temperature, the crystal electric field level splitting was determined with ${\mathrm{\ensuremath{\Delta}}}_{1}({\mathrm{\ensuremath{\Gamma}}}_{6})=85\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and ${\mathrm{\ensuremath{\Delta}}}_{2}({\mathrm{\ensuremath{\Gamma}}}_{8})\ensuremath{\approx}200\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, the latter being a quartet in this cubic symmetry. An effective magnetic moment ${\ensuremath{\mu}}_{\mathrm{eff}}\ensuremath{\approx}3{\ensuremath{\mu}}_{B}$ is evaluated for the ${\mathrm{\ensuremath{\Gamma}}}_{7}$ ground state, while at high temperature the value for a ${\mathrm{Yb}}^{3+}$ ion is observed. At low temperature this compound shows the typical behavior of a magnetically frustrated system undergoing a change of regime at a characteristic temperature ${T}^{*}\ensuremath{\approx}200\phantom{\rule{0.16em}{0ex}}\mathrm{mK}$ into of Fermi-liquid-type ``plateau'' of the specific heat: ${C}_{m}{/T|}_{T\ensuremath{\rightarrow}0}$ = const. The change in the temperature dependence of the specific heat coincides with a maximum and a discontinuity in respective inductive and dissipative components of the ac susceptibility. More details about the nature of this ground state are revealed by the specific heat behavior under applied magnetic field.

We have investigated the local low-energy excitations in CeRu4Sn6, a material discussed recently in the framework of strongly correlated Weyl semimetals, by means of Ce M-5 resonant inelastic x-ray scattering (RIXS). The availability of both F-2(5/2) and F-2(7/2) excitations of the Ce 4f(1) configuration in the spectra allows for the determination of the crystal-electric field (CEF) parameters that explain quantitatively the high-temperature anisotropy of the magnetic susceptibility. The absence of an azimuthal dependence in the spectra indicates that all CEF states are close to being rotational symmetric. We show further that the non-negligible impact of the (sic)(6)(0) parameter on the ground state of CeRu4Sn6 leads to a reduction of the magnetic moment mu(c) due to multiplet intermixing. This improves the agreement between CEF calculations and the experimentally determined magnetic susceptibility considerably at low temperatures. Deviations that persist at low temperatures for fields within the tetragonal plane are attributed to the Kondo interaction between 4f and conduction electrons. The RIXS results are consistent with inelastic neutron scattering data and are compared to the predictions from ab initio based electronic structure calculations.