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The recent progress in CuMnAs and Mn3X (X = Sn, Ge, Pt) shows that antiferromagnets (AFMs) provide a promising platform for advanced spintronics device innovations. Most recently, a switchable Fermi‐arc is discovered by the ARPES technique in antiferromagnet NdBi, but the knowledge about electron‐transport property and the manipulability of the magnetic structure in NdBi is still vacant to date. In this study, SdH oscillations are successfully verified from the Dirac surface states (SSs) with 2‐dimensionality and nonzero Berry phase. Particularly, it is observed that the spin‐flop transition only appears when the external magnetical field is applied along [001] direction, and features obvious hysteresis for the first time in NdBi, which provides a powerful handle for adjusting the spin texture in NdBi. Crucially, the DFT shows the Dirac cone and the Fermi arc strongly depend on the high‐order magnetic structure of NdBi and further reveals the orbital magnetic moment of Nd plays a crucial role in fostering the peculiar SSs, leading to unveil the mystery of the band‐splitting effect and to manipulate the electronic transport, high‐effectively, in the thin film works in NdBi. It is believed that this study provides important guidance for the development of new antiferromagnet‐based spintronics devices based on cutting‐edge rare‐earth monopnictides. [ABSTRACT FROM AUTHOR]

The 2D chromium telluride family (CrxTey) is an outstanding candidate for creating high‐density and dissipationless nanodevices because of its high Curie temperature, chiral spin patterns, and large saturation magnetic moment. However, the precise magnetic exchange mechanism and crucial phase transitional property of CrxTey must be fully analyzed. Herein, a large‐area CrTe (x:y = 1:1) single‐crystalline films deposited on an Al2O3 substrate. Based on the analysis of critical isothermal magnetization around the Curie temperature TC = 201 K and the modified Arrott plot, the precise critical exponents β = 0.386(3) and γ = 1.391(2) are obtained. Both their reliability and accuracy are also verified by Kouvel–Fisher theory, Widom scaling law, and scaling equation. Moreover, using the renormalization group theory, it is confirmed that CrTe belongs to a quasi‐2D Heisenberg‐like behavior with long‐range interactions. Finally, the density functional theory calculations indicate that, near the Fermi level, the CrTe band structure is mainly composed of Cr atom. The spin‐polarized density of states shows that the total magnetic moments are determined mainly by the polarized spin‐up t2g electron of Cr atom. This work is an important asset for a series of CrxTey materials in future spintronic applications. [ABSTRACT FROM AUTHOR]

Low-dimensional magnetism, including the Haldane phase and large single ion anisotropy (large-D) phase, has received ongoing attention due to their potential applications in quantum computing and molecular spintronics. However, the lack of materials possessing S = 1 one-dimensional spin-chain with antiferromagnetic intrachain interaction (J) and single ion anisotropy (D) has hindered the investigation and practical implementation of this topic. In this study, iron(II) phthalocyanine (FePc) crystals in β-phase (β-FePc) hosting molecular chains along the b axis are prepared as revealed by X-ray diffraction (XRD). The molecular orientation is found to be almost upright within the naturally cleaved bc plane as determined by synchrotron-based near-edge X-ray absorption fine structure spectroscopy (NEXAFS). β-FePc crystals exhibit clear magnetic anisotropy with the easy plane perpendicular to the b axis, antiferromagnetic intrachain exchange interaction and a large D value. These results demonstrate experimentally that the β-FePc crystal is a new antiferromagnetic spin-1 large-D phase material. This discovery expands the frontiers of low-dimensional magnetism research in organic molecular crystals, providing a new platform to study the topological quantum phase transition in one-dimensional spin chains. [ABSTRACT FROM AUTHOR]

The performance of iron-based superconductors in high magnetic fields plays an important role for their practical application. In this work, we measured the magnetostriction and magnetization of BaFe1.908Ni0.092As2 single crystals using pulsed magnetic fields up to 60 T and static magnetic fields up to 33 T, respectively. A huge longitudinal magnetostriction (of the order of 10–4) was observed in the direction of twin boundaries. The magnetization measurements evidence a high critical-current density due to strong bulk pinning. By using magnetization data with an exponential flux-pinning model, we can reproduce the magnetostriction curves qualitatively. This result shows that the magnetostriction of BaFe1.908Ni0.092As2 can be well explained by a flux-pinning-induced mechanism. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms for forming skyrmionic spin configurations at room temperature is essential for exploring the applicable spintronics devices based on topological spin textures. In this work, the anisotropic magnetic properties and critical behavior are investigated in noncollinear itinerant magnet PrMn2Ge2. The strongly anisotropic magnetic interactions and magnetic field and temperature induced antiferromagnetic to ferromagnetic transition are observed. The critical behavior of high temperature ferromagnetic transition at 331 K was analyzed, and the critical exponents β = 0.335, γ = 0.878, and δ = 3.617 are extracted by the modified Arrott plot method, which lie between the values of long-range mean-field and short-range three-dimensional theories, demonstrating that PrMn2Ge2 possesses multiple magnetic interactions. This is also confirmed by the moderated interaction function, which is decay as J(r) ∼ r − 4.69 . Therefore, the competition of multiple magnetic interactions in PrMn2Ge2 is analogous to what has been observed in GdRu2Si2 and could be the origin of skyrmionic bubbles observed at room temperature. [ABSTRACT FROM AUTHOR]

Spin-orbit coupled honeycomb magnets with the Kitaev interaction have received a lot of attention due to their potential of hosting exotic quantum states including quantum spin liquids. Thus far, the most studied Kitaev systems are 4d/5d-based honeycomb magnets. Recent theoretical studies predicted that 3d-based honeycomb magnets, including Na2Co2TeO6 (NCTO), could also be a potential Kitaev system. Here, we have used a combination of heat capacity, magnetization, electron spin resonance measurements alongside inelastic neutron scattering (INS) to study NCTO's quantum magnetism, and we have found a field-induced spin disordered state in an applied magnetic field range of 7.5 T < B (⊥ b-axis) < 10.5 T. The INS spectra were also simulated to tentatively extract the exchange interactions. As a 3d-magnet with a field-induced disordered state on an effective spin-1/2 honeycomb lattice, NCTO expands the Kitaev model to 3d compounds, promoting further interests on the spin-orbital effect in quantum magnets. The honeycomb lattice with a spin-orbit interaction can give rise to exotic quantum states. With the measurements of bulk properties and inelastic neutron scattering, Lin et al demonstrate the existence of a field induced spin-disordered state in Na2Co2TeO6 and extend the Kitaev model to 3d system. [ABSTRACT FROM AUTHOR]

We have presented the structural, surface morphology, magnetic and resistivity data for perovskite LaMnO3 epitaxial thin films which are fabricated on well-oriented (001) LaAlO3 substrates by pulsed laser deposition technique. X-ray diffraction 𝜃 – 2 𝜃 linear scans and reciprocal space mapping measurement confirm that the out-of-plane and in-plane epitaxial relationship are LMO(001)/LAO(001) and LMO(110)/LAO(110), respectively. Surface roughness determined by atomic force microscopy was no more than 0.3 nm. In the whole studied temperature range, all films only show a paramagnetic behavior instead of any magnetic phase transitions. Correspondingly, the electron transport behaviors always exhibit an insulting state as the temperature changes from high to low. However, we find that none of theoretical models can individually be used to understand their conductive mechanisms. Further studies indicated that charge carries of high and low temperature region obey adiabatic and nonadiabatic small polaronic hopping mechanisms, respectively. This finding offers new ways of exploiting the abnormal ferromagnetism in LaMnO3 multilayer thin films. [ABSTRACT FROM AUTHOR]

High-quality epitaxial LaCoO3 (LCO) thin films have been deposited on SrTiO3 (STO) substrates with pulsed laser deposition (PLD). We find that the LCO films undergo a typical ferromagnetic–paramagnetic (FM–PM) phase transition at ∼80 K. To understand the nature of magnetic phase transition, various methods, including the modified Arrott plot and critical isotherm analysis, were used to determine the critical exponents, which are β = 0.754(1) with a Curie temperature TC = 79.8(8) K and γ = 1.52(2) with TC = 79.9(2) K. The reliability of these critical exponents was confirmed using the Widom scaling relation and the scaling hypothesis. Further analysis revealed that the spin coupling within the LCO films exhibits two-dimensional (2D) long-range magnetic interaction and the magnetic exchange distance decays as J(r) ∼ r−(3.46). Our critical behavior analysis may shed new light on the further understanding of the origin of FM and the relatively fixed TC in LCO thin films. [ABSTRACT FROM AUTHOR]

While charge-ordering transition is well established in the oxygen-deficient layered cobaltite YBaCo2O5, there has been no evidence for the transition in the analogous compound GdBaCo2O5 either from neutron diffraction or from magnetic susceptibility experiments. In this paper, we present comparative studies on the electron spin resonance (ESR) of Gd3+ ions in Y1-xGdxBaCo2O5 (x = 0.01, 0.25, and 1) polycrystalline samples. Magnetic susceptibility was also performed for comparison with the ESR results. It was found that charge-ordering transition for Y0.75Gd0.25BaCo2O5 revealed by the susceptibility is also manifested in the characters of the ESR data. The similar temperature-evolution of the ESR parameters for GdBaCo2O5 provides a support for the existence of charge-ordering transition, although no characteristic of the transition is evidenced from susceptibility experiments, which can be understood as being hidden by dominant paramagnetism of Gd3+ ions in this compound. We have interpreted the temperature variation of ESR parameters in terms of electron localization associated with Co2+/Co3+ charge ordering. [ABSTRACT FROM AUTHOR]

Co3Sn2S2, a quasi-two-dimensional system with a kagome lattice, has been found to be a magnetic Weyl semimetal recently. In this work, the anisotropies of magnetization and transport properties of Co3Sn2S2 were investigated. The high field measurements reveal a giant magnetocrystalline anisotropy with an out-of-plane saturation field of 0.9 kOe and an in-plane saturation field of 230 kOe at 2 K, showing a magnetocrystalline anisotropy coefficient Ku up to 8.3 × 105 J m−3, which indicates that it is extremely difficult to align the small moment of 0.29 μB/Co on the kagome lattice from the c axis to the ab plane. The out-of-plane angular dependence of Hall conductivity further reveals strong anisotropies in the Berry curvature and ferromagnetism, and the vector directions of both are always parallel with each other. For the in-plane situation, the longitudinal and transverse measurements for both I // a and I ⊥ a cases show that the transport on the kagome lattice is isotropic. These results provide the essential understanding of the magnetization and transport behaviors for the magnetic Weyl semimetal, Co3Sn2S2. [ABSTRACT FROM AUTHOR]

The magnetic and electronic transport properties of the lightly doped SrRu1-x Fex O3 (x ≤ 0.15) have been studied. All the samples show a paramagnetic-ferromagnetic phase transition and hysteresis effect. With the increase of Fe, the temperature of magnetic phase transition decreases but coercive field increases indicting the existence of antiferromagnetic interaction and magnetic-crystalline anisotropy. In low temperature, all the doping samples exhibit an insulating behavior while metal feature appears only at x ≤ 0.10 samples. The induced disorder suppresses the itinerant property of Ru 4d electron due to Fe random occupation. As a result, the ferromagnetism is weakened and metal-insulator transition is suppressed. [ABSTRACT FROM AUTHOR]

We report a detailed study of magnetic and transport properties in perovskite manganites Nd0.55Sr0.45Mn1-xGaxO3 (0.00≤x≤0.20). The Ga substitution induces the B-site disorder together with a distinct suppression of the metal-insulator transition and ferromagnetic-paramagnetic transition. Due to an appearance of inhomogeneous magnetic clusters, the Griffiths-like phase is observed in 0.08≤x≤0.10 compounds. Meanwhile, with the increase of Ga concentration, the carriers self-trap into magnetic polarons. Because the oxygen sublattice distortion causes the variation of the phonon density of state, an additional Raman vibrative mode appears in the system. [ABSTRACT FROM AUTHOR]

The electronic transport and magnetism in half-doped Nd0.50Ca0.25Sr0.25MnO3 manganites have been investigated. Contrary to general half-doped system, it only displays a paramagnetic-ferromagnetic phase transition associated with an insulator-metal transition instead of with any features of charge ordering. With the decrease of temperature, an electronic phase separation and spin glass state occur in low temperature. We suggest that the A-site cation disorder induced by the size mismatch between Sr2+ ion and Ca2+ ion is mainly responsible for this phenomenon. [ABSTRACT FROM AUTHOR]

The structural, Hall effect, electronic transport, and magnetic properties of Ge0.96−xBixFe0.04Te epitaxial thin film as prepared by pulsed laser deposition technique were reported. X-ray diffraction patterns including linear scans and phi scans confirmed that all films are high quality epitaxy and crystallinity. With the substitution of high valence Bi for Ge element, we found that the previous carriers of hole were changed to electron, which was testified by the negative slopes obtained from the measurements of Hall effect under different temperatures. The electronic transports show a typical semiconductor behavior and can be understood by the small polaron hopping model because the lattice distortions increase the electron-phonon interaction. An obvious ferromagnetic properties occur in the high Bi-doping Ge0.64Bi0.32Fe0.04Te rather than in that with low Bi-doping concentration, indicating that the ferromagnetic establishment is entirely dependent on carrier's transmissions. The first-principles calculation performed on this system also reveals that the ferromagnetic state exactly exists in the present n-type diluted magnetic semiconductors with Bi co-dopants. [ABSTRACT FROM AUTHOR]

The Cr ion doped Y-type hexaferrite Ba0.5Sr1.5Zn2Fe11.4Cr0.6O22 has been found to be a promising magnetoelectric material for the non-zero spontaneous electric polarization that can be reversed by a relatively low magnetic field. However, it remains an open question what the underlying mechanism of the magnetoelectric correlation is and how this correlation evolves with the varying temperature and magnetic field. Here we establish a detailed phase diagram via the combined measurements and analyses of magnetization, dielectric constant, and electric polarization. Various magnetic and ferroelectric phases are discovered for different scales of temperature and magnetic field, as well as the complicated and intriguing phase transitions. A newly emerging transition at 183 K separates the low-field ferroelectric phase into two regions with reversal and non-reversal polarizations, respectively, which is rarely observed among various magnetoelectric ferrites. Possible field-dependent magnetic structures are proposed to qualitatively explain this transition. [ABSTRACT FROM AUTHOR]

We investigated the magnetic properties of a geometrically frustrated magnet of ZnFe2O4 nanoparticles by carrying out the comprehensive measurements of dc magnetization and ac susceptibility. Spin glass is confirmed to occur in this weakly Fe(Zn)-ionic-inversed sample. The common characteristics of spin glass including the aging, the memory, and the rejuvenation effects were observed. By using the critical-power law to study the spin dynamics, the spin-glass transition temperature Tg is obtained to be 18 K and the dynamic exponent zν is 8.0. The weak exchange interaction disorder introduced by the ferrimagnetic JAB interaction, together with the weak nonmagnetic dilute disorder induced by the ionic inversion, is responsible for the formation of spin glass in the ZnFe2O4 nanoparticles. [ABSTRACT FROM AUTHOR]

We report electrical transport and anisotropic magnetic properties of Mn-intercalated 2H-TaS2, a layered transition-metal dichalcogenide with a hexagonal structure. The single crystal MnxTaS2 with x = 1/3 exhibits a transition from paramagnetism to ferromagnetism near 70 K, below which both the magnetoresistance and magnetization properties present strong anisotropic behavior. Its anisotropic magnetoresistance effect and in-plane soft ferromagnetic property suggests that this layered material would be a good candidate for exploring the physics of two-dimensional ferromagnetism. [ABSTRACT FROM AUTHOR]

We report a detailed study of magnetic properties in manganite (LaPr)CaMnO. In contrast to the usual beliefs, it shows an abnormal upturn deviation from the Curie-Weiss law on the inverse susceptibility curve. Such a non-Griffiths-like phase is further confirmed from the inverse double integrated intensities of electron paramagnetic resonance spectrum. Because La $$^{3+}$$ ions are substituted by Pr $$^{3+}$$ ions with 50% concentrations, the ratio of three ions (La $$^{3+}$$ , Pr $$^{3+}$$ , Ca $$^{2+}$$ ) is close to 1 on A-site sublattice. As a result, some short-range antiferromagnetic (CO AFM) phases come into being in the system due to the existence of localized charge ordering states. Therefore, the upturn deviation from Curie-Weiss law originates from the appearance of short-range CO AFM correlations above $$T_{\text{C}}$$ . Additionally, a magnetic field-driven-metamagnetic transition is found, which gives a main contribution for the large magnetic entropy change (MEC) observed in this sample. Both the Arrott plot and the renormalized MEC curves testify that this transition belongs to first-order magnetic transition. The insignificant hysteresis loop indicate that the inevitable thermal hysteresis can be ignored in the present first-order material implying that it is a potential candidate for the cryogenic temperature magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The pyrochlore iridatehas been investigated by means of the electron paramagnetic resonance spectroscopy. A magnetic transition at20 K is found in addition to the transition at130 K, which has not been reported previously. The phase transition at, which corresponds to a resistivity transition, is resulted from the long-range spin ordering ofions in all-in/all-out state. However, the magnetic transition at, which is regardless of resistivity transition, is not caused bybutions. Both of the magnetic transitions are irrelevant to the lattice distortion. We suggest that the competition between the enhanced paramagnetism ofions and thef–dinteraction should be responsible for the magnetic transition at. [ABSTRACT FROM PUBLISHER]

In this work, we perform a systematic study of the lattice dynamics of IrTeusing temperature dependence of X-ray diffraction experiment. It is found that the lattice structural symmetry of IrTechanges from trigonal (space group) into monoclinic () below the phase transition temperature (). Remarkably, experimental results show that the trigonal cell still insists below, which coexists intrinsically with the monoclinic cell. After the phase transition, the proportion of the monoclinic cell almost remains unchanged. The structure phase transition temperatures determined from cooling and warming are240 K and265 K, respectively. Moreover, the superlattice phase is found with13.5, which is suggested to be caused by the destabilization of polymeric Te–Te bonds. [ABSTRACT FROM AUTHOR]

In this paper, we present the investigations of electron paramagnetic resonance on perovskite manganite PrSrMnO and Ga-doped PrSrMnGaO. The temperature dependent paramagnetic resonance spectra parameters (effective g-factor, peak-to-peak linewidth Δ H and double integrated intensities) have been used to study the paramagnetic spin correlations and spin dynamics. The gradual increase of effective g-factor is attributed to the presence of orbital ordering above T. The model fittings of temperature dependent double integrated intensities reveal Arrhenius law is appropriate for describing PrSrMnGaO instead of PrSrMnO system. As for PrSrMnO, the broadening of linewidth with the temperature increase origins from the contribution of small polaron hopping in the PM regime. However, as for PrSrMnGaO, the broadening of EPR linewidth can be understood with the spin-lattice relaxation mechanism. [ABSTRACT FROM AUTHOR]

The effects of As doping on the superconductivity and magnetism in the TlKFeSe superconductor are studied. We find that the As doping does not significantly change the occupancy at the Fe-site, meaning a certain amount of Fe ions changes its valence from 2+ to 3+. The superconductivity is gradually suppressed with increasing As doping. The magnetic measurements suggest that though the As doping does not destroy the antiferromagnetic order in the system, it induces an increase in the staggered magnetic moment. These results suggest that the TlKFeSe system is a system with intrinsic phase separation. The change in the valence state of Fe could be a possible reason for the suppression of superconductivity. [ABSTRACT FROM AUTHOR]

Electron paramagnetic resonance studies have been performed on the perovskite manganite Pr0.55Sr0.45MnO3. The various spectrum parameters including line width, effective g-value and double-integrated intensities have been analyzed in detail. The changes of g-value and linewidth are indicative of the presence of strong spin-lattice interaction in the paramagnetic regime. The lattice distortion causes the appearance of localized carriers and the formation of a small polaron. Therefore, the large activation energy obtained from two different methods implies that a strong spin-lattice correlation exists in Pr0.55Sr0.45MnO3. [ABSTRACT FROM AUTHOR]

Structural and magnetic properties of Bi0.5 Ca0.5-xBaxMnO3 (x = 0, 0.03, 0.05, 0.07 and 0.10) samples with charge ordering (CO) state and C-type antiferromagnetic (AFM) magnetic structure have been studied systematically. With increasing Ba-doping level, both CO and AFM are weakened. From the micro-magnetic analysis, we clarify the ambiguity about the Néel temperature TN in bismuth-based perovskite manganites. We find that the paramagnetic (PM)-CO/AFM transition temperature TCO at high temperature is the onset temperature of the PM-AFM transition, while customarily so-called TN at low temperature indicates the finish of the PM-AFM transition. Both the macro- and micro-magnetic data show that, in all the samples, only AFM state coexists with PM matrix below CO transition and above TN, while AFM state coexists with ferromagnetic (FM) state and PM state at lower temperature below TN. [ABSTRACT FROM AUTHOR]

We perform oxygen doping experiments in the CaFeAsF and CaFeCoAsF compounds. In the parent compound CaFeAsF, partial replacement of F by O leads to an increase of resistivity and a weakening of spin-density wave transition, indicating that the out-of-plane disorder strongly affects the electronic and magnetic properties of the system. In the CaFeCoAsFO system, the doping of oxygen leads to the suppression of superconductivity, reflecting the importance of Ca-F layer disorder in this system. [ABSTRACT FROM AUTHOR]

In this work, we report a study on the infrared transmission spectroscopy of the double perovskite Ba2YMoO6. At 300 K, three bands are observed at ∼255.1 cm-1, ∼343.4 cm-1, and ∼561.5 cm-1, which are related to the motion between the cation Ba2+ and the anion YMO6-2, the Y-O stretching motion, and the stretching vibration of the MoO6 octahedron, respectively. These modes continue to harden upon cooling owing to the shrink of the lattice constant. When the temperature decreases to T≤130 K around which the spin singlet dimer begins to form, an additional phonon mode appears at ∼611 cm-1, suggesting the occurrence of local distortion of MoO6 octahedra. With further decrease of the temperature, its intensity enhances and its peak position keeps unchanged. These results indicate that the formation of the spin singlet dimers is accompanied with the occurrence of the local structure distortion of MoO6 octahedra, providing evidence for the strong spin-phonon coupling in the double perovskite Ba2YMoO6. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated the magnetism of multiferroic CoCr2O4. With decreasing temperature, CoCr2O4 first undergoes a ferrimagnetic transition at TC then a long-range spiral spin transition at TS followed by a magnetic lock-in transition at TL. Coercive force manifests different slopes in different magnetic phases. Upon cooling the sample at 100 Oe to 5 K then warming back, the magnetization displays irreversibility between the cooling and warming sequence at temperatures below TL. The irreversible behavior under the thermal-cycling is inert to magnetic field up to 45 kOe, indicating the coexistence of incommensurate and commensurate spiral orders. Both TS and TL are increased with the application of high pressure, which implies that the magnetic frustration is enhanced upon the shrinkage of lattice. The spin-lattice coupling is also revealed by infrared spectrum. [ABSTRACT FROM AUTHOR]

One method of calculating critical exponents based on the field dependence on magnetic entropy change was applied to study critical behavior in Pr0.55Sr0.45MnO3. By using the obtained critical exponents, the modified Arrott plot [A. Arrott and J. E. Noakes, Phys. Rev. Lett. 19, 786 (1967)] is consistent with that by using conventional method. The calculated critical exponents not only obey the scaling theory, but also inosculate the deduced results from the Kouvel-Fisher method [J. S. Kouvel and M. E. Fisher, Phys. Rev. 136, A1626 (1964)]. It eliminates the drawback due to utilization of multistep nonlinear fitting in a conventional manner. Therefore, this means can be applied to investigate critical behavior. [ABSTRACT FROM AUTHOR]

Publisher's Note: "On the anisotropies of magnetization and electronic transport of magnetic Weyl semimetal Co3Sn2S2" [Appl. Phys. This article was originally published online on 22 November 2019 with minor grammatical errors. All online versions of the article were corrected on 25 November 2019; the article is correct as it appears in the printed version of the journal. [Extracted from the article]

The magnetic states of the BaFe2-xCoxAs2 single crystal samples have been studied by magnetization and electron spin resonance measurements. We find a transformation of the Fe2+ spin state from high temperature high-spin state to low temperature low-spin state, indicating a small crystal field splitting energy. In the superconducting samples, both the magnetization and electron spin resonance results suggest an itinerant behavior of the system. [ABSTRACT FROM AUTHOR]

In this work, we successfully synthesize the single crystal Cr11Ge19. The magnetism of the noncentrosymmetric Cr11Ge19 with itinerant ferromagnetic ground state is thoroughly investigated on the single crystal. Based on the variation measurements including the angular rotation, temperature, and magnetic field dependence of magnetization, we find that this material exhibits strong magnetic anisotropy along the c-axis. To clearly reveal the magnetic interactions, the critical behavior is studied using the modified Arrott plot, the Kouvel-Fisher method, and the critical isotherm technique. Combining these different methods, three main critical exponents (β, γ, and δ) are obtained. The critical exponent β is close to the theoretical prediction of a three-dimensional XY model with spin-dimensionality n = 2, indicating two-dimensional magnetic coupling. Meanwhile, the critical exponent γ suggests that the magnetic interaction is of long-range type with magnetic exchange distance decaying as J(r) ≈ r−4.61. We propose that the ferromagnetic ground state of Cr11Ge19 is formed by the polarized magnetic moments along the c-axis, while the long-range magnetic coupling is established within the ab plane. [ABSTRACT FROM AUTHOR]

Quantum spin liquid (QSL) is a novel state of matter which refuses the conventional spin freezing even at 0 K. Experimentally searching for the structurally perfect candidates is a big challenge in condensed matter physics. Here we report the successful synthesis of a new spin-1/2 triangular antiferromagnet YbMgGaO4 with symmetry. The compound with an ideal two-dimensional and spatial isotropic magnetic triangular-lattice has no site-mixing magnetic defects and no antisymmetric Dzyaloshinsky-Moriya (DM) interactions. No spin freezing down to 60 mK (despite θw ~ −4 K), the power-law temperature dependence of heat capacity and nonzero susceptibility at low temperatures suggest that YbMgGaO4 is a promising gapless (≤|θw|/100) QSL candidate. The residual spin entropy, which is accurately determined with a non-magnetic reference LuMgGaO4, approaches zero (<0.6%). This indicates that the possible QSL ground state (GS) of the frustrated spin system has been experimentally achieved at the lowest measurement temperatures. [ABSTRACT FROM AUTHOR]

We study the effects of S-doping on the microstructure, magnetic and transport properties of the Tl0.4K0.4Fe2−ySe2−xSx superconductor. At low doping level (x ⩽ 0.8), the samples exhibit behaviors similar to those of the parent sample, i.e., the occurrence of phase separation into a Fe-vacancy phase, a charge ordering phase and an undistorted phase; the presence of a “hump”-like feature in the resistivity curves; and the development of antiferromagnetic order well above room temperature. In sharp contrast, the samples with x ⩾ 1.0 all exhibit metallic-like behavior without displaying superconductivity. And these samples are chemically phase separated into a S-poor Tl0.4K0.4Fe2−ySe2−xSx-phase and a S-rich Tl0.4K0.4Fe2−yS2-phase. Interestingly, the Fe-vacancy phase is absent in these samples, accompanied with the disappearance of semiconducting-like conductivity at high temperature and the depression of superconductivity. The charge ordering phase is responsible for the metallic behavior in heavily doped samples. [ABSTRACT FROM AUTHOR]