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Multiferroic materials can realize the mutual coupling between force, electricity, magnetism and other physical fields, and have important application prospects in the field of small size, fast response and low power consumption of magnetoelectric devices. GaFeO3 is a highly promising multiferroic material featuring high spontaneous magnetization and polarization beyond room temperature. In this study, Ferroelectric Mgx Ga1 - x FeO3 (x = 0. 02, 0. 05, 0. 07 and 0. 10) single crystals with a diameter of about 7 mm were grown by light floating zone method. The effect of Mg2 + on the saturation magnetization and magnetic transition temperature of GaFeO3 (GFO) crystals were studied. The structure and phase of the crystal were analyzed through XRD, the results show that all the prepared samples correspond to the diffraction characteristics of the standard crystal card library GFO (PDF#76-1005), and no other heterophase appears. The XRD refinement results indicate that, the crystal structure is orthogonal and its space group is Pna21. As the concentration of Mg2 + rises, the lattice constant and cell volume initially increase and subsequently decrease. Additionlly, the magnetic properties of the crystal were studied through a comprehensive physical property measurement system, the magnetic transition temperature and saturation magnetization of the grown crytals also increase firstly and then decrease with the increase of Mg2 + doping content. When the Mg2 + doping amount is 0. 07, the magnetic transition temperature and saturation magnetization reach the maximum values of 187. 82 K and 8. 75 emu/g, respectively, which achieves the purpose of doping modification. [ABSTRACT FROM AUTHOR]

We report the anomalous Nernst effect (ANE) in bulk La1-xNaxMnO3 (x = 0.02, 0.05, 0.1, and 0.3) samples whose ferromagnetic Curie temperature (TC) is tunable from 251 K to 310 K. The ANE voltage abruptly increases at TC and decreases for T < TC. The maximum value of ANE is achieved for x = 0.1, which shows the highest magnetization value in the series. The temperature dependent ANE (T < TC) is analyzed with the help of dc resistivity and longitudinal thermopower data using Mott's relation, and it is found that the ANE in La1-xNaxMnO3 is dominated by skew scattering. [ABSTRACT FROM AUTHOR]

We report the anomalous Nernst effect (ANE) in bulk La1-xNaxMnO3 (x = 0.02, 0.05, 0.1, and 0.3) samples whose ferromagnetic Curie temperature (TC) is tunable from 251 K to 310 K. The ANE voltage abruptly increases at TC and decreases for T < TC. The maximum value of ANE is achieved for x = 0.1, which shows the highest magnetization value in the series. The temperature dependent ANE (T < TC) is analyzed with the help of dc resistivity and longitudinal thermopower data using Mott's relation, and it is found that the ANE in La1-xNaxMnO3 is dominated by skew scattering. [ABSTRACT FROM AUTHOR]

The magnetic entropy changes of ΔSM(T,H) around the magnetic transition temperature (TC) have been investigated by the scaling method in a two-dimensional ferromagnetic semiconductor (2D FS) CrI3 single crystal. The critical parameters based on ΔSM(T,H) have been obtained. The ΔSM(T,H) under different magnetic fields can be scaled into a single curve independent of external field and temperature. The magnetic entropy is about 3.21 J/kg K at applied magnetic field H = 4.5 T. The critical parameters n, b, and c obtained from magnetic entropy ΔSM(T,H) are about 0.62(1), 0.69(2), and 1.30(3), respectively. The value of n is close to that of the 3D Heisenberg model. The temperature dependent n at different magnetic fields scales into one universal line above TC and deviates the scaling line at low temperatures. The deviation can be attributed to the strong uniaxial anisotropy effect in CrI3. The result is helpful for understanding the origin of the magnetic phase transition in 2D FSs. [ABSTRACT FROM AUTHOR]

The magnetic entropy changes of ΔSM(T,H) around the magnetic transition temperature (TC) have been investigated by the scaling method in a two-dimensional ferromagnetic semiconductor (2D FS) CrI3 single crystal. The critical parameters based on ΔSM(T,H) have been obtained. The ΔSM(T,H) under different magnetic fields can be scaled into a single curve independent of external field and temperature. The magnetic entropy is about 3.21 J/kg K at applied magnetic field H = 4.5 T. The critical parameters n, b, and c obtained from magnetic entropy ΔSM(T,H) are about 0.62(1), 0.69(2), and 1.30(3), respectively. The value of n is close to that of the 3D Heisenberg model. The temperature dependent n at different magnetic fields scales into one universal line above TC and deviates the scaling line at low temperatures. The deviation can be attributed to the strong uniaxial anisotropy effect in CrI3. The result is helpful for understanding the origin of the magnetic phase transition in 2D FSs. [ABSTRACT FROM AUTHOR]

Vertically aligned nanocomposites (VAN) combined ferrimagnetic CoFe2O4 with non-magnetic CeO2 ((CoFe2O4)x:(CeO2)1–x) in different phase ratios (x=10%, 30% to 50%) have been grown by a pulsed laser deposition technique. Various unique magnetic domain structures form based on the VAN compositions and growth conditions. Anisotropic and tunable ferrimagnetic properties have been demonstrated. These ordered ferrimagnetic nanostructures have been incorporated into YBa2Cu3O7–δ thin films as both cap and buffer layers to enhance the flux pinning properties of the superconducting thin films. The results suggest that the ordered magnetic VAN provides effective pinning centers by both defect and magnetic nanoinclusions. [ABSTRACT FROM AUTHOR]

Magnetic properties of compacted Sm0.1Ca0.9MnO3 particles with 25 and 60 nm average sizes have been investigated. Particular attention has been paid to Griffiths-like features at temperatures above magnetic transition temperature TC and to the system glassiness at low temperatures. Griffiths-like features in inverse magnetic susceptibility of Sm0.1Ca0.9MnO3 nanoparticles have been linked to the presence of short range ferromagnetically correlated spin clusters above TC. Glassy behavior has been revealed in temperature and frequency dependence of ac-susceptibility, temperature and field dependence of thermoremanent and isothermoremanent magnetization, and time decay of the remanent magnetization. Experiments revealed the major impact of the glassy component on magnetic properties of investigated nanoparticles. The magnetic relaxation associated with glassy features was found to be much more pronounced in smaller particles, where a formation of collective state in an ensemble of phase separated nanoparticles may take place. Thermomagnetic irreversibility found in Sm0.1Ca0.9MnO3 nanoparticles has been linked to martensitic strain effects. [ABSTRACT FROM AUTHOR]

Ab-initio calculations were performed to study the electronic and magnetic properties of boron doped XS (X = Zn and Cd) systems. The structural stability of doped systems is analyzed in terms of formation energy and found that B@S site in ZnS is more energetically favorable than that of B@S in CdS system. Our calculations show that B-doping at S-site (B@S) induced magnetism in XS structures, which can be explained on the basis of electronegativity difference between the dopant and host atoms. It is evident that B 2 p orbitals are playing the major role to generate magnetism in both (ZnS and CdS) doped systems. In contrast, B-doping at Zn/Cd sites in XS structures, leads the systems to n -type non-magnetic conductor. Furthermore, the impact of B-doping at different S sites is studied to probe the stable magnetic ground state. Finally, the magnetic transition temperature (T c) is also computed. • B@S ZnS doped system is more energetically favorable than that of B@S CdS. • B@S doping exhibits magnetism in both ZnS and CdS systems. • B@Zn doped ZnS and B@Cd doped CdS systems show n -type nonmagnetic behavior. [ABSTRACT FROM AUTHOR]

The "isospin-phonon" coupling in Sr2IrO4 is investigated by temperature dependent phonon Raman scattering. Anomalous behavior in the frequency of all studied optical phonons is observed below the magnetic transition temperature TN ∼ 240 K. The strongest effect is detected for the A1g mode at 272 cm−1 associated with the modulation of the Ir–O–Ir bond angle. Additionally, the A1g mode at 560 cm−1 shows a Fano asymmetric lineshape sensitive to TN, supporting the existence of low energy (∼70 meV) electronic excitations that are renormalized by the magnetic order. These results reveal the characteristics of the interaction between the crystal lattice and electronic degrees of freedom in this "spin-orbit" entangled Mott insulator. [ABSTRACT FROM AUTHOR]

The "isospin-phonon" coupling in Sr2IrO4 is investigated by temperature dependent phonon Raman scattering. Anomalous behavior in the frequency of all studied optical phonons is observed below the magnetic transition temperature TN ∼ 240 K. The strongest effect is detected for the A1g mode at 272 cm−1 associated with the modulation of the Ir–O–Ir bond angle. Additionally, the A1g mode at 560 cm−1 shows a Fano asymmetric lineshape sensitive to TN, supporting the existence of low energy (∼70 meV) electronic excitations that are renormalized by the magnetic order. These results reveal the characteristics of the interaction between the crystal lattice and electronic degrees of freedom in this "spin-orbit" entangled Mott insulator. [ABSTRACT FROM AUTHOR]

Control of the Néel vector in antiferromagnetic (AFM) materials is one of the challenges preventing their use as active device components. Several methods have been investigated such as exchange bias, electric current, and spin injection, but little is known about strain-mediated anisotropy. This study of the AFM L10-type MnX alloys MnIr, MnRh, MnNi, MnPd, and MnPt shows that a small amount of strain effectively rotates the direction of the Néel vector by 90° for all of the materials. For MnIr, MnRh, MnNi, and MnPd, the Néel vector rotates within the basal plane. For MnPt, the Néel vector rotates from out-of-plane to in-plane under tensile strain. The effectiveness of strain control is quantified by a metric of efficiency and by direct calculation of the magnetostriction coefficients. The values of the magnetostriction coefficients are comparable with those from ferromagnetic materials. These results indicate that strain is a mechanism that can be exploited for control of the Néel vectors in this family of antiferromagnets. [ABSTRACT FROM AUTHOR]

Highlights • The Mössbauer spectroscopy study of dependence of Morin transition on particle sizes. • The relative concentrations of coexisting WF and AF phases were determined by MS. • The finite-scaling theoretical model with log-normal size distribution was assigned. • For hematite nanoparticles with mean diameter lower then ~8 nm, the T M is suppressed. • The magnetic moments in WF phase at 4.2 K deviate out off the basal plane. • The Debye temperature of hematite ~610 K was determined. Abstract A spin-reorientation transition from a weakly ferromagnetic (WF) to an antiferromagnetic (AF) spin ordering in hematite (α-Fe 2 O 3) during cooling occurs at Morin temperature (T M ∼264 K for bulk). The transition is strongly size dependent and T M generally decreases with the decreasing volume of the particles. For particles smaller than approximately ∼20 nm, the Morin transition may be even suppressed and disappears entirely as near-surface spins deviate strongly from the antiferromagnetic easy axis. We report an investigation on nanoparticles prepared by hydrothermal method and sol–gel technique (in silica) of pure α-Fe 2 O 3 phase as confirmed by XRD (space group R- 3 c , lattice parameters a = 5.038(2) Å, c = 13.772(12) Å) differing in the median size derived by TEM: 5.6 nm, 26 nm, 42 nm and 103 nm. By means of Mössbauer spectra acquired between 4.2 and 300 K, we determined the relative concentrations of magnetic phases (WF and AF) within the 57Fe enriched sample and searched for the best finite-scaling theoretical model (mean-field, 3D Heisenberg, Ising) describing the derived size dependence of Morin temperature of the nanoparticles with a log-normal size distribution. The comparison of relevant parameters derived from the fit of experimental data by theoretical model is consistent with the 3D Heisenberg model with scaling parameter λ = 1.4, Morin temperature of bulk material T M (∞) = 265(1) K and correlation length ξ 0 = 8.1(2) nm or Ising model with λ = 1.6, T M (∞) = 265(1) K and ξ 0 = 9.4(2) nm. [ABSTRACT FROM AUTHOR]

Based upon a superconducting transition edge sensor (TES), the Meissner-TES is a relatively new type of high resolution cryogenic thermometer which employs the magnetic transition of a superconductor to measure temperature. We have improved the signal-to-noise for DC sensing by a factor of 30 compared to our prior effort and developed a new AC mode which uses an oscillating magnetic field and a lock-in technique with much lower magnetic noise than the DC mode. The thermometer was tuned in situ over a range of operating temperatures 10–50 times larger than the transition width of the superconductor, using an applied persistent magnetic field. The DC mode can have sensitivity better than 1 nK for 100 s averaging, and the AC mode has sensitivity better than 120 nK for very small applied magnetic fields near 14 nT and 100 s averaging. The Meissner-TES can be applied to high sensitivity infrared sensing, optical power scale realization, and the study of temperature-dependent phase transitions. [ABSTRACT FROM AUTHOR]

Electronic structure and magnetic properties for GdFeSi have been studied theoretically from a first-principles density functional calculation. The energy band structure is calculated in a local spin density approximation (LSDA)+Hubbard U approach (LSDA+U). For Gd atoms, seven spin up 4f bands are fully occupied, while the spin down 4f hole levels are completely unoccupied and well above the Fermi level. The calculated magnetic moment of Gd is 7.20 μB, leading to a total magnetization of 7.1 μB per formula unit due to the small induced negative moments at Fe and Si atoms. The intersites exchange coupling parameters Jij of the Heisenberg model have been derived using a linear-response method based on the calculated band structure. The exchange coupling parameters for the nearest Gd-Gd pair (JGd-Gd) is 0.19 mRy. JGd-Gd decreases rapidly with increasing the intersites distance and shows a Ruderman-Kittel-Kasuya-Yoshida-like oscillation. The estimated Curie temperature is about 145 K from the calculated exchange coupling parameters based on the mean-field approximation, in good agreement with the experimental value (TC exp. =135 K). [ABSTRACT FROM AUTHOR]

Abstract The perovskite-type LaFe 0.5 Ni 0.5 O 3 belonging to the rhombohedral (space group R -3 c) crystal structure has been synthesized for which we have identified a magnetic transition at T 1 = 8 K corresponding to the minimum observed in the derivative of temperature dependent magnetization. A bifurcation in the ZFC and FC curves is observed below T 1 that suggests a frustrated magnetic behavior. The non-zero moment above T 1 hints the possibility of the presence of a high-temperature magnetic transition in the material. The resistivity of LaFe 0.5 Ni 0.5 O 3 evolves as a function of temperature similar to that of a semiconductor. Mott's variable range hopping governs the conduction mechanism of the material. Presence of various anisotropy terms and inhomogeneous magnetic interactions lead to the presence of antiferromagnetic and ferromagnetic interfaces, which eventually causes a magnetic exchange bias and magnetic hysteresis in resistivity. We have also observed direction dependent magnetoresistance in the material. [ABSTRACT FROM AUTHOR]

Abstract—: We have studied the caloric and magnetic properties of alloys in the MnAs-ZnGeAs2 eutectic system. The results demonstrate that the heat effect and temperature range of the ferromagnetic-to-paramagnetic phase transformation depend on the crystallite size of manganese arsenide. Reducing the crystallite size to ≤60 nm causes the heat effect of the transformation to disappear, significantly changes the temperature range of the magnetic transition, and raises the Curie temperature of the alloy to 351 K. [ABSTRACT FROM AUTHOR]

Abstract A series of Gd 60 Co 40- x Fe x (x = 0, 5, 10, 15, 20) amorphous ribbons were synthesized by melt-spinning method, and the addition of Fe is detrimental for thermal stability as well as glass forming ability of the alloys. With the increasement of Fe content, the magnetic transition temperature increases firstly and then decreases with the peak of 239 K obtained in Gd 60 Co 30 Fe 10 , while the magnetic entropy change |Δ S M | reduces gradually. This phenomenon is possibly caused by variation of predominant exchange interaction from ferromagnetic to ferrimagnetic. Among these alloys, Gd 60 Co 30 Fe 10 , Gd 60 Co 25 Fe 15 and Gd 60 Co 20 Fe 20 represent table-like magnetocaloric effect of 4.4 ± 0.1 Jkg−1K−1, 4.0 ± 0.1 Jkg−1K−1 and 3.8 ± 0.1 Jkg−1K−1 in wide temperature ranges of 201–238 K, 178–228 K and 178–218 K under an applied field H of 5 T, which is probably ascribed to the local structural inhomogeneity in the amorphous matrix. This hypothesis could be confirmed by the deviation of exponent n (|Δ S M | ∝ H n ) and the universal behavior of |Δ S M |- T curves. The present study is expected to enhance the knowledge about the influence of additional elements on magnetocaloric effect and improve the performance of amorphous refrigerants in the Ericsson-cycle near room temperature. Graphical abstract Image 1 Highlights • The Fe replacement is adverse to thermal stability of Gd 60 Co 40- x Fe x glassy alloy. • Table-like magnetocaloric effect was obtained in alloys with x = 10, 15 and 20. • Above phenomenon is due to local structural inhomogeneity in the amorphous matrix. • The power law and universal behavior of magnetic entropy change were constructed. [ABSTRACT FROM AUTHOR]

It has been observed that in nanowires (diameter ∼ 100 nm) of a rare-earth (RE) transition metal (TM) alloy Gd x Co 1− x ( x  = 0.4) the magnetic transition temperatures like the magnetization compensation temperatures ( T c m ) can be shifted upward by nearly 350 K compared to that of the bulk and be made as high as 850 K. The saturation magnetization ( M S ) remains high over the whole temperature range compared to that the bulk and at room temperature the enhancement in M S is 33%. This enhances the applicability of the RE-TM alloy to well above the room temperature. The magnetic experiments were carried out in the temperature range 80 K–1100 K on the alloy nanowires grown by electrochemical synthesis in the nanopores of Anodic Aluminium Oxide (AAO) templates. It has been established that the large shift in the T c m is linked to qualitative change in the nature of the anisotropy energy E A on size reduction, in particular in the temperature derivative d E A / d T that reaches more or less temperature independent value in the nanowires. [ABSTRACT FROM AUTHOR]

Electrical resistance R and specific heat C were measured to study the physical properties of the novel compound Nd5CuSn3 which crystallizes in the hexagonal Hf5CuSn3-type structure. Nd ions occupy two non-equivalent sites. The values of R and C showed distinct anomalies at the magnetic transition temperature TM of 56.3 K. The increments of TM in the magnetic fields are consistent with the material being in a ferro- or ferri-magnetic state at temperatures below TM. [ABSTRACT FROM AUTHOR]

Electrical resistance R and specific heat C were measured to study the physical properties of the novel compound Nd5CuSn3 which crystallizes in the hexagonal Hf5CuSn3-type structure. Nd ions occupy two non-equivalent sites. The values of R and C showed distinct anomalies at the magnetic transition temperature TM of 56.3 K. The increments of TM in the magnetic fields are consistent with the material being in a ferro- or ferri-magnetic state at temperatures below TM. [ABSTRACT FROM AUTHOR]

Fe 2 P-based materials are attracting great interest for their giant magnetocaloric effect making them highly promising candidates for a new energy efficient-magnetic cooling technology. In light of recent results reported in the MnFe(P,Si) and MnFe(P,Si,B) series, here we revisit the effect of Ge substitution for P. By fixing the Mn/Fe ratio to unity while exploring a large range of Ge content, we isolate the effect Ge plays as metalloid element. In contrast to other metalloids (like Si, B or As), Ge substitution for P is found to spectacularly increase the Curie temperature, while preserving the first-order character of the transition. As a consequence, Ge substitution for P provides a mean to achieve giant magnetocaloric performances up to high temperatures (at least 465 K). In addition, the moment formation in MnFe(P,Ge) is investigated using an element specific and orbital selective magnetization probe, x-ray magnetic circular dichroism. The magnetic moments carried by Mn atoms are found to be significantly larger than that of Fe, providing a direct experimental support to reported band structure calculations and neutron diffraction experiments. [ABSTRACT FROM AUTHOR]

The effect of indium doping on structural and magnetic properties of Y-type hexaferrite Ba 0.5 Sr 1.5 Zn 2 (Fe 1- x In x ) 12 O 22 ( x  = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) prepared by the solid state reaction method was investigated. The Rietveld refinement method was used to analyze the X-ray diffraction patterns. The magnetic transition temperatures associated with the proper-screw spin phase to the collinear ferrimagnetic spin phase transition can be efficiently modulated by varying indium content. The magnetic transition temperature increases to a maximum with indium content x  = 0.04 and then decreases with x , suggesting the possibility that electrically controlled magnetization reversal can be can be effectively tailored by varying indium content. The saturation magnetization at room temperature was decreased as increasing indium content, which can be explained as the metal ions occupation. It is worthy to note that the coercivity of In-doped samples was decreased drastically compared that of undoped sample, which is probably resulted from the reduction in anisotropy field with substitution of In 3+ for Fe 3+ . The In-doped hexaferrite Ba 0.5 Sr 1.5 Zn 2 (Fe 1- x In x ) 12 O 22 may be potential candidates for application in magnetoelectric devices. [ABSTRACT FROM AUTHOR]

The article looks at a study which report the intermediate composition system to be a unique host of two disconnected, thermal-equilibrium topological skyrmion phases. Topics discussed include conventional skyrmion crystal phase stabilized by thermal fluctuations and restricted to exist just below the magnetic transition temperature, stability of this new disordered skyrmion phase is due to a cooperative interplay between the chiral magnetism and elemental geometrically frustrated spin liquid.

Y(Mn 0.8 Fe 0.2 ) 1-x Ti x O 3 (x = 0.05 and 0.1) and 0.98Y(Mn 0.8 Fe 0.2 )O 3 -0.02SrTiO 3 ceramics with hexagonal structure were prepared, and the microstructure, magnetic, dielectric and electrical characteristics combined with the charge states of magnetic ions were evaluated. Ti single-substitution did not cause the microcrack formation in the Y(Mn 0.8 Fe 0.2 )O 3 ceramics. However, spontaneous microcracking took place in the Ti, Sr co-substitution ceramics. All the ion-substituted ceramics were predominantly antiferromagnetic with weak ferromagnetic properties at low temperature. The antiferromagnetic transition temperature was decreased upon Ti substitution whereas the magnetic ordering temperature was increased upon Ti, Sr co-substitution. The varied valence distributions of the Fe and Mn ions contributed to the modified magnetic properties. By Ti substitution, the dielectric loss and conductivity of the ceramics were obviously reduced, and this should be related to the decreased Mn 2+ and Fe 2+ contents in the mixed valence structure. [ABSTRACT FROM AUTHOR]

Polycrystalline Bi1−xBaxFeO3 (0 ≤ x ≤ 0.30) samples have been prepared by two stage solid state reaction method. The surface texture of the prepared material exhibited a uniform grain distribution with minor empty space suggesting that the density of the pelletized samples is high and grain size is found to decrease with Ba substitution. An important observation is the stabilization of a dielectric anomaly near the magnetic transition temperature in temperature dependent dielectric studies which is ascribed to the presence of magnetoelectric (ME) coupling. This ME coupling effect has been demonstrated by measuring the effect of varying magnetic fields on the dielectric constant. The dielectric constant increased with increasing applied magnetic field giving a coupling coefficient (εr(H) − εr(0))/εr(0) of 1% at H = 5 kOe at room temperature which demonstrate the importance of these material from application point of view. The dielectric constant is high at low frequencies and is found to decrease at moderate frequencies indicating the Maxwell-Wagner contribution to the dielectric response. The increase in Ba content and temperature resulted in an increase in bulk resistance and exhibits a typical negative temperature coefficient of resistance behavior. A temperature dependent and non-Debye type of relaxation process is revealed by impedance spectroscopic studies. The conductivity spectra revealed the presence of hopping mechanism in the electrical transport process and the activation energies lying in the range from 0.45 to 0.70 eV indicate that the conduction of oxygen vacancies through hopping mechanism. [ABSTRACT FROM AUTHOR]

We have studied the magnetic properties of the multipolar ordering compounds Ce ( Pd 1 − x Pt x ) 3 S 4 with 0.00 ≤ x ≤ 0.53 by means of magnetic susceptibility and magnetization measurements. In CePd 3 S 4 , a simultaneous phase transition of the antiferro quadrupolar (AFQ) ordering and ferro magnetic (FM) ordering has been observed at 6.3 K. It has been suggested that the primary order parameter of CePd 3 S 4 is the quadrupole moments, and it has not been understood why the FM ordering occurs at very high temperature which is almost the same magnetic transition temperature of GdPd 3 S 4 . GdPd 3 S 4 shows an antiferromagnetic (AFM) transition at 5.8 K. With increasing Pt substitution in CePd 3 S 4 , the FM transition temperature T C ( x ) is rapidly suppressed to 2.4 K for x ≃ 0.3 and approaches asymptotically to 1.9 K ( x = 0.53 ) . The results of magnetization curve suggest that the ordered state below T C ( x ) remains FM and AFQ ordered state for the whole range of x . For x ≥ 0.29 , T C ( x ) reaches at around 2 K, a new AFM transition was observed at T N ( x ) ≃ 7 K . We determined the T − x phase diagram, and discuss the phase transitions at T C ( x ) and T N ( x ) . The results suggest the possibility of the presence of the correlation between the magnetic interaction and the quadrupole interaction, and the correlation is not understood based on the previous multipolar model. [ABSTRACT FROM AUTHOR]

Epitaxial orthorhombic YMn0.9Ru0.1O3 films with different thickness have been grown on (001)-SrTiO3 substrates by pulsed laser deposition (PLD). The crystal structure is well investigated by X-ray Diffraction. It is found that the out-of-plane parameter c slowly increases with decreasing thickness of samples because of the tensile strain between the films and substrates along c axis. The lengths of in-plane Mn-O bonds expand with the enhancement of strains, which is proved by Raman scatting. The magnetic measurements reveal that there exist two magnetic transition temperatures TN1 and TN2. The TN1 is close to that of orthorhombic YMnO3 bulk. With decreasing thickness of the films, TN1 keeps almost constant because of the small stain along c-axis. TN2, however, obviously increases from 117 K to 134 K, which could be related to the expansion of in-plane Mn-O bonds. Results show that the magnetic transition temperature of YMn0.9Ru0.1O3 films can be sensitively manipulated by the strain of the films. [ABSTRACT FROM AUTHOR]

The magnetic properties of diamond shaped graphene quantum dots have been investigated by varying their sizes with the Monte Carlo simulation. The magnetizations and magnetic susceptibilities have been studied with dilutions x (magnetic atom), several sizes L (carbon atom) and exchange interaction J between the magnetic atoms. The all magnetic susceptibilities have been situated at the transitions temperatures of each parameters. The obtained values increase when increases the values of x , L and J . The effect of exchanges interactions and crystal field on the magnetization has been discussed. The magnetic hysteresis cycles for several dilutions x , sizes L , exchange interactions J and temperatures T . The magnetic coercive increases with increasing the exchange interactions and decreases when the temperatures values increasing. [ABSTRACT FROM AUTHOR]

The effect of Ni 2+ doping on the magnetic and magnetocaloric properties of La 0.7 Ca 0.3 MnO 3 manganites synthesized via the auto-combustion method is reported. The aim of studying Ni 2+ -substituted La 0.7 Ca 0.3 Mn 1 − x Ni x O 3 ( x = 0 , 0.02 , 0.07 , and 0.1) manganites was to explore the possibility of increasing the operating temperature range for the magnetocaloric effect through tuning of the magnetic transition temperature. X-ray diffraction analysis confirmed the phase purity of the synthesized samples. The substitution of Mn 3+ ions by Ni 2+ ions in the La 0.7 Ca 0.3 MnO 3 lattice was also corroborated through this technique. The dependence of the magnetization on the temperature reveals that all the compositions exhibit a well-defined ferromagnetic to paramagnetic transition near the Curie temperature. A systematic decrease in the values of the Curie temperature is clearly observed upon Ni 2+ doping. Probably the replacement of Mn 3+ by Ni 2+ ions in the La 0.7 Ca 0.3 MnO 3 lattice weakens the Mn 3+ –O–Mn 4+ double exchange interaction, which leads to a decrease in the transition temperature and the magnetic moment in the samples. By using Arrott plots, it was found that the phase transition from ferromagnetic to paramagnetic is second order. The maximum magnetic entropy changes observed for the x = 0 , 0.02 , 0.07 , and 0.1 composites was 0.85, 0.77, 0.63, and 0.59 J/kg K, respectively, under a magnetic field of 1.5 T. In general, it was verified that the magnetic entropy change achieved for La 0.7 Ca 0.3 Mn 1 − x Ni x O 3 manganites synthesized via the auto-combustion method is higher than those reported for other manganites with comparable Ni 2+ -doping levels synthesized via standard solid state reaction. The addition of Ni 2+ increases the value of the relative cooling power as compared to that of the parent compound. The highest value of this parameter (∼60 J/kg) is found for a Ni-doping level of 2% around 230 K in a field of 1.5 T. [ABSTRACT FROM AUTHOR]

Tailorable magnetic state near room temperature is very promising for several technological, including magnetocaloric applications. Here using first-principle alloy theory, we determine the Curie temperature ( T C ) of a number of equiatomic medium- and high-entropy alloys with solid solution phases. All calculations are performed at the computed lattice parameters, which are in line with the available experimental data. Theory predicts a large crystal structure dependence of T C , which explains the experimental observations under specified conditions. The sensitivity of the magnetic state to the crystal lattice is reflected by the magnetic exchange interactions entering the Heisenberg Hamiltonian. The analysis of the effect of composition on T C allows researchers to explore chemistry-dependent trends and design new multi-component alloys with pre-assigned magnetic properties. [ABSTRACT FROM AUTHOR]

The structure, magnetic and electronic transport properties of the compounds Mn 3 Sn 1- x Zn x C (0 ≤ x ≤ 0.5) are investigated. The studies have shown that Zn-doping in the anti-perovskite structure Mn 3 SnC reduces the cell parameter, but the compounds Mn 3 Sn 1- x Zn x C remain cubic anti-perovskite structure. When the temperature is reduced, the magnetization curve changes from PM-FM for Mn 3 SnC and Mn 3 Sn 0.9 Zn 0.1 C into PM-FM-AFM for Mn 3 Sn 1- x Zn x C(x ≥ 0.2). With the increase of doping amount x, both the Tc and the T T reduce, but when x = 0.5, they are raised. In addition, the magnetization of Mn 3 Sn 1- x Zn x C is reduced as the doping amount increases. For Mn 3 Sn 1- x Zn x C(x = 0, 0.1, 0.2,0.3, 0.4, 0.5) compounds, there exists an anomalous increase in resistivity at a certain temperature that is in agreement with their magnetic transition temperature, and doping Zn in Mn 3 SnC reduces the resistivity of Mn 3 SnC. [ABSTRACT FROM AUTHOR]

The physical properties of the Multiferroïc lead-free 0.9BiFeO 3 -0.1Ba[Ti 0.95 (Yb 0.5 Nb 0.5 ) 0.05 ]O 3 ceramic were investigated by in-situ Mössbauer spectroscopy, X-ray diffraction (XRD), dielectric measurements and Raman scattering. Both BiFeO 3 and 0.9BiFeO 3 -0.1Ba[Ti 0.95 (Yb 0.5 Nb 0.5 ) 0.05 ]O 3 ceramics underwent in-situ Mössbauer spectroscopy in the temperature range of 300 K to 653 K and the parameters of hyperfine interactions were determined. The magnetic transition temperature T N of our doped sample was of 568 K, which was lower than that of BiFeO 3 . This reduction of T N originated from the presence of different exchange constants resulting from the weakening of J Fe-Fe . The deviation of the reduced magnetic hyperfine field H(T)/H(0) as a function of the reduced temperature T/T N from the Brillouin curve of Fe 3+ (S = 5/2) for the three sextets and the determination of the critical exponent β, of 0.375 ± 0.022 in the range of 0.01 < 1-T/T N < 0.5 revealed a 3D magnetic long range order phase transition. The complexity of the spatial spin structure was a result of the canting of antiferromagnetically ordered spins of BiFeO 3 . Our findings revealed the effect of the non-magnetic substituents Ba and Yb/Nb/Ti in A and B sites, respectively on the magnetic properties. Around the magnetic transition temperature, both isomer shift evolution and quadruple splitting distribution showed pronounced anomalies associated with the onset of magnetic ordering. The Debye temperature (θ D ) was deduced to be of 257 ± 21 K. These results revealed 0.9BiFeO 3 -0.1Ba[Ti 0.95 (Yb 0.5 Nb 0.5 ) 0.05 ]O 3 as a promising material for piezoelectric devices. XRD analyses were performed for temperatures from 300 K up to 750 K. Gradual structural evolution, as temperature increased, exhibited an isostructural phase transition and an anomaly in the evolution of lattice parameters and the unit cell volume as well as a significant shift in the atomic positions near the magnetic transition temperature T N . These behaviors indicate magnetoelastic coupling. The temperature dependence of the real part of dielectric permittivity and dielectric loss (tan δ) was investigated over a wide range of temperatures at 1 kHz. During its evolution, an anomaly was observed at 568 K; which corresponded to the magnetic transition temperature T N . Raman scattering spectra were measured in the temperature range from 303 K to 728 K. Drastic changes, especially that of the three two-phonon modes centered at around 1000-1500 cm −1 , were the results of magnetic rearrangement and atomic displacement leading to both modulating magnetic exchange interaction and polarization state. All these results prove the magnetoelectric coupling of 0.9BiFeO 3 -0.1Ba[Ti 0.95 (Yb 0.5 Nb 0.5 ) 0.05 ]O 3 ceramic. [ABSTRACT FROM AUTHOR]

Macroscopic magnetic properties are analyzed using Valence Bond theory. Commonly the critical temperature TC for magnetic systems is associated with a maximum in the energy-based heat capacity Cp(T). Here a more broadly applicable definition of the magnetic transition temperature TC is described using the spin moment expectation value (i.e., applying the spin exchange density operator) instead of energy. Namely, the magnetic capacity Cs(T) reflects variation in the spin multiplicity as a function of temperature, which is shown to be related to ∂[χT(T)]/∂T. Magnetic capacity Cs(T) depends on long-range spin interactions that are not relevant in the energy-based heat capacity Cp(T). Differences between Cs(T) and Cp(T) are shown to be due to spin order/disorder within the crystal that can be monitored via a Valence Bond analysis of the corresponding magnetic wave function. Indeed the concept of the Boltzmann spin-alignment order is used to provide information about the spin correlation between magnetic units. As a final illustration, the critical temperature is derived from the magnetic capacity for several molecular magnets presenting different magnetic topologies that have been experimentally studied. A systematic shift between the transition temperatures associated with Cs(T) and Cp(T) is observed. It is demonstrated that this shift can be attributed to the loss of long-range spin correlation. This suggests that the magnetic capacity Cs(T) can be used as a predictive tool for the magnetic topology and thus for the synthetic chemists. [ABSTRACT FROM AUTHOR]