Spin-reorientation phase transitions that involve the rotation of a crystal$'$s magnetization have been well characterized in distorted-perovskite oxides such as the orthoferrites. In these systems spin reorientation occurs due to competing rare-earth and transition metal anisotropies coupled via $f$-$d$ exchange. Here, we demonstrate an alternative paradigm for spin reorientation in distorted perovskites. We show that the $R_2\mathrm{CuMnMn_4O_{12}}$ (R = Y or Dy) triple A-site columnar-ordered quadruple perovskites have three ordered magnetic phases and up to two spin-reorientation phase transitions. Unlike the spin-reorientation phenomena in other distorted perovskites, these transitions are independent of rare-earth magnetism, but are instead driven by an instability towards antiferromagnetic spin canting likely originating in frustrated Heisenberg exchange interactions, and the competition between Dzyaloshinskii-Moriya and single-ion anisotropies.
Na$_2$Co$_2$TeO$_6$ has recently been proposed to be a Kitaev-like honeycomb magnet. To assess how close it is to realizing Kitaev quantum spin liquids, we have measured magnetization and specific heat on high-quality single crystals in magnetic fields applied along high-symmetry directions. Small training fields reveal a weak but canonical ferrimagnetic behavior below 27 K, which cannot be explained by the zigzag antiferromagnetic order alone and suggests coexisting Néel-type order of moments canted away from the zigzag chains. Moderate fields in the honeycomb plane suppress the thermal trans…
Ground-state and finite-temperature properties of $S=1/2$ Heisenberg ladders with a ferromagnetic leg, an antiferromagnetic leg, and antiferromagnetic rungs are studied. It is shown that a partial ferrimagnetic phase extends over a wide parameter range in the ground state. The numerical results are supported by an analytical calculation based on a mapping onto the nonlinear $σ$ model and a perturbation calculation from the strong-rung limit. It is shown that the partial ferrimagnetic state is a spontaneously magnetized Tomonaga--Luttinger liquid with incommensurate magnetic correlation, which …
Ferroelectric properties of cubic chiral magnet Cu2OSeO3 can emerge due to the spin noncollinearity induced by antiferromagnetic cantings. These cantings are the result of the Dzyaloshinskii-Moriya interaction and in many ways similar to the ferromagnetic cantings in weak ferromagnets. An expression for the local electric polarization is derived, including terms with gradients of magnetization M(r). When averaged over the crystal the electric polarization has a non-vanishing part associated with the anisotropy of the crystal point group 23. In the framework of the microscopic theory, it is sho…
Hexagonal YMnO$_{3}$ is a prototype antiferromagnet which exhibits multiferroic behavior with the ferroelectric and magnetic transitions occurring at different temperatures. We observe an out-of-plane canting of the Mn$^{3+}$ magnetic moments using resonant X-ray diffraction (RXD) in a single crystal of this material. These canted moments result in the symmetry-forbidden (0,0,1) magnetic Bragg reflection, which is observed at the Mn $L_{2,3}$ absorption edges. We also observe an unexpected difference in the RXD spectral shapes at different temperatures. Using ab initio calculations, we explore…
The spin ordering and spin-charge coupling in LuFe2O4 were investigated on the basis of density functional calculations and Monte Carlo simulations. The 2:1 ferrimagnetism arises from the strong antiferromagnetic intra-sheet Fe3+-Fe3+ and Fe3+ -Fe2+ as well as some substantial antiferromagnetic Fe2+-Fe3+ inter-sheet spin exchange interactions. The giant magnetocapacitance at room temperature and the enhanced electric polarization at 240 K of LuFe2O4 are explained by the strong spin-charge coupling.
Effect of the coupling to mobile carriers on the 120$^\circ$ antiferromagnetic state is investigated in a ferromagnetic Kondo lattice model on a frustrated triangular lattice. Using a variational calculation for various spin orderings up to a four-site unit cell, we identify the ground-state phase diagram with focusing on the lightly-doped region. We find that an electron doping from the band bottom immediately destabilizes a 120$^\circ$ coplanar antiferromagnetic order and induces a noncoplanar three-sublattice ordering accompanied by an intervening phase separation. This noncoplanar phase ha…
It is shown that nearest-neighbor antiferromagnetic interactions of identical Ising spins on imbalanced bipartite lattice and imbalanced bipartite hierarchical fractal result in ferrimagnetic order instead of antiferromagnetic one. On some crystal lattices dilute Ising antiferromagnets may also become ferrimagnets due to the imbalanced nature of the magnetic percolation cluster when it coexists with the percolation cluster of vacancies. As evidenced by the existing experiments on $Fe_pZn_{1-p}F_2$, such ferrimagnetism is inherent property of bcc lattice so thermodynamics of these compounds at …
We consider analytically and numerically an anisotropic spin-$\frac{1}{2}$ delta-chain (sawtooth chain) in which exchange interactions between apical and basal spins are ferromagnetic and those between basal spins are antiferromagnetic. In the limit of strong anisotropy of exchange interactions this model can be considered as the Ising delta chain with macroscopic degenerate ground state perturbed by transverse quantum fluctuations. These perturbations lift the ground state degeneracy and the model reduces to the basal XXZ spin chain in the magnetic field induced by static apical spins. We sho…
Coherent canted ferrimagnetism and higher-order anisotropy in the nodal-line magnetic semiconductor Mn3Si2Te6
Chungnam National University（忠南国立大学）；Pohang University of Science and Technology（浦项工科大学）；Korea Basic Science Institute（韩国基础科学研究所）；Pusan National University（釜山国立大学）；Kyungpook National University（庆北国立大学）；Laboratoire National des Champs Magnétiques Intenses, CNRS, LNCMI, Université Grenoble Alpes, Univ Toulouse 3, INSA Toulouse, EMFL（法国国家强磁场实验室）
Antiferromagnetic and ferro/ferrimagnetic orders are typically exclusive in nature, thus, their co-existence in atomic-scale proximity is expected only in heterostructures. Breaking this paradigm and broadening the range of unconventional magnetic states, we report here on an atomic-scale hybrid spin state, which is stabilized in three-dimensional crystals of the polar antiferromagnet Co$_2$Mo$_3$O$_8$ by magnetic fields applied perpendicular to the \emph{Co} honeycomb layers and possesses a spontaneous in-plane ferromagnetic moment. Our microscopic spin model, capturing the observed field dep…
We report $^{51}$V NMR, $μ$SR and zero applied field $^{63,65}$Cu NMR measurements on powder samples of Sr-vesignieite, SrCu$_3$V$_2$O$_8$(OH)$_2$, a $S = 1/2$ nearly-kagome Heisenberg antiferromagnet. Our results demonstrate that the ground state is a $\mathbf{q} = 0$ magnetic structure with spins canting either in or out of the kagome plane, giving rise to weak ferromagnetism. We determine the size of ordered moments and the angle of canting for different possible $\mathbf{q} = 0$ structures and orbital scenarios, thereby providing insight into the role of the Dzyaloshinskii-Moriya (DM) inte…
Tight-binding Hamiltonians with single and multiple orbitals exhibit an intriguing array of magnetic phase transitions. In most cases the spin ordered phases are insulating, while the disordered phases may be either metallic or insulating. In this paper we report a Determinant Quantum Monte Carlo study of interacting electrons in a geometry which can be regarded as a two-dimensional Periodic Anderson Model with depleted interacting ($f$) orbitals. For a single depletion, we observe an enhancement of antiferromagnetic correlations and formation of localized states. For half of the $f$-orbitals …
We use a non-equilibrium many-body theory that engages the elements of transient coherence, correlation, and nonlinearity to describe changes in the magnetic and electronic phases of strongly correlated systems induced by femtosecond nonlinear photoexcitation. Using a generalized tight--binding mean field approach based on Hubbard operators and including the coupling of the laser field, we describe a mechanism for simultaneous insulator--to--metal and anti-- to ferro--magnetic transition to a transient state triggered by non-thermal ultrafast spin and charge coupled excitations. We demontrate,…
The Slater-Pauling rule states that L21 Heusler compounds with 24 valence electrons do never exhibit a total spin magnetic moment. In case of strongly localized magnetic moments at one of the atoms (here Mn) they will exhibit a fully compensated half-metallic ferrimagnetic state instead, in particular, when symmetry does not allow for antiferromagnetic order. With aid of magnetic and anomalous Hall effect measurements it is experimentally demonstrated that Mn1.5V0.5FeAl follows such a scenario. The ferrimagnetic state is tuned by the composition. A small residual magnetization, that arises due…
We report the observation of magnetic domains in the exotic, antiferromagnetically ordered all-in-all-out state of Nd$_2$Zr$_2$O$_7$, induced by spin canting. The all-in-all-out state can be realized by Ising-like spins on a pyrochlore lattice and is established in Nd$_2$Zr$_2$O$_7$ below 0.31 K for external magnetic fields up to 0.14 T. Two different spin arrangements can fulfill this configuration which leads to the possibility of magnetic domains. The all-in-all-out domain structure can be controlled by an external magnetic field applied parallel to the [111] direction. This is a result of …
Using density functional calculations, we find that the newly synthesized Ca$_2$FeOsO$_6$ has the high-spin Fe$^{3+}$ ($3d^5$)-Os$^{5+}$ ($5d^3$) state. The octahedral Os$^{5+}$ ion has a large intrinsic exchange splitting, and its $t_{2g\uparrow}^3$ configuration makes the spin-orbit coupling ineffective. Moreover, there is a strong antiferromagnetic (AF) coupling between the neighboring Fe$^{3+}$ ($S$ = 5/2) and Os$^{5+}$ ($S$ = -3/2), but the AF couplings within both the fcc Fe$^{3+}$ and Os$^{5+}$ sublattices are one order of magnitude weaker. Therefore, a magnetic frustration is suppresse…
The magnetic properties of GdBaMn_{2}O_{5.0}, which exhibits charge ordering, are studied from 2 to 400 K using single crystals. In a small magnetic field applied along the easy axis, the magnetization M shows a temperature-induced reversal which is sometimes found in ferrimagnets. In a large magnetic field, on the other hand, a sharp change in the slope of M(T) coming from an unusual turnabout of the magnetization of the Mn sublattices is observed. Those observations are essentially explained by a molecular field theory which highlights the role of delicate magnetic interactions between Gd^{3…
We introduce a microscopic model for electron doped manganites that explains the mechanism of the observed transition from $G$-type antiferromagnetic ($G$-AF) to $C$-type antiferromagnetic ($C$-AF) order under increasing doping by double exchange mechanism. The model unravels the crucial role played by $e_g$ orbital degrees of freedom and explains the observed metal-to-insulator transition by a dimensional crossover at the magnetic phase transition. The specific heat and the spin canting angle found for the $G$-AF phase agree with the experimental findings. As a surprising outcome of the theor…
We show that a superstructure of antiferromagnetically interacting Fe$^{3+}$ ($S=5/2$) ions in double perovskites AFe$_{1/2}$M$_{1/2}$O$_{3}$ exhibits a ferrimagnetic ordering below $T_{fe} \approx 5.6J_1$ ($J_1/k_B \sim 50$~K), which is close to room temperature. Small clusters of the same structure exhibit a superparamagnetic behavior at $T \lesssim T_{fe}$. The possibility of formation of such clusters explains the room-temperature (superpara)magnetism in 3$d$-metal based oxides.
We synthesized a series of GdFe$_{1-x}$Co$_x$AsO polycrystalline samples ($0 \leq x \leq 1$) by using a solid state reaction method and present a systematic study on the physical properties by means of electrical resistivity $ρ(T)$, magnetic susceptibility $χ(T)$ and specific heat $C(T)$. The parent compound GdFeAsO undergoes a spin-density-wave (SDW) transition associated with Fe 3d-electrons around 130 K, followed by an antiferromagnetic (AFM) transition of Gd at $T^\textup{Gd}_\textup{N} \approx$ 4 K. The SDW transition is quickly suppressed by Fe/Co substitution and superconductivity appea…
We study the ground-state properties of the S=1/2 antiferromagnetic Heisenberg model on the Union Jack strip lattice by using the exact-diagonalization and density matrix renormalization group methods. We confirm a region of the intermediate-magnetization state between the Neel-like spin liquid state and the conventional ferrimagnetic state of Lieb-Mattis type. In the intermediate-state, we find that the spontaneous magnetization changes gradually with respect to the strength of the inner interaction. In addition, the local magnetization clearly shows an incommensurate modulation with long-dis…
Strongly correlated electrons in layered perovskite structures have been the birthplace of high-temperature superconductivity, spin liquid, and quantum criticality. Specifically, the cuprate materials with layered structures made of corner sharing square planar CuO$_4$ units have been intensely studied due to their Mott insulating grounds state which leads to high-temperature superconductivity upon doping. Identifying new compounds with similar lattice and electronic structures has become a challenge in solid state chemistry. Here, we report the hydrothermal crystal growth of a new copper tell…
We have analyzed the dynamics of a single hole doped in a canted antiferromagnet using the t-J model. Within the self consistent Born approximation we have found that the hole propagates at two different energy scales along the antiferromagnetic and the ferromagnetic components of the canted order, respectively. While the many body quasiparticle excitation has its origin in the coherent coupling of the hole with the magnon excitations of the antiferromagnetic component, the ferromagnetic component gives rise to a free like hole motion at higher energies. We have found a non-trivial behavior of…
We carried out a comprehensive study of magnetic critical behavior in single crystals of ternary chalcogenide FeCr$_2$Te$_4$ that undergoes a ferrimagnetic transition below $T_c$ $\sim$ 123 K. Detailed critical behavior analysis and scaled magnetic entropy change indicate a second-order ferrimagentic transition. Critical exponents $β= 0.30(1)$ with $T_c = 122.4(5)$ K, $γ= 1.22(1)$ with $T_c = 122.8(1)$ K, and $δ= 4.24(2)$ at $T_c$ $\sim$ 123 K suggest that the spins approach three-dimensional Ising ($β$ = 0.325, $γ$ = 1.24, and $δ$ = 4.82) model coupled with the attractive long-range interacti…
Neutron measurements on Ca{1-x}La{x}MnO3 (0.00 <= x <= 0.20) reveal the development of a liquid-like spatial distribution of magnetic droplets of average size ~10 Angstroms, the concentration of which is proportional to x (one cluster per ~60 doped electrons). In addition, a long-range ordered ferromagnetic component is observed for ~0.05 < x < ~0.14. This component is perpendicularly coupled to the simple G-type antiferromagnetic (G-AFM) structure of the undoped compound, which is a signature of a G-AFM + FM spin-canted state. The possible relationship between cluster formation and the stabil…
Based on the extended Hubbard model we calculate the energy of stripe and spiral ground states. We find that uniform spirals get favored by a large $t'/t$ ratio but are unstable at small doping towards stripes and checkerboard textures with spin canting. The structure of these inhomogeneities also depends on t'/t and the associated spin currents may induce a small lattice distortion associated with local dipole moments. We discuss a new kind of stripe which appears as a domain wall of the antiferromagnetic (AF) order parameter with a fractional change of the phase of the AF order. For large |t…
We show that in the antiferromagnetic ferroelectric BaNiF4 the Dzyaloshinskii-Moriya interaction leads to a small canting of the magnetic moments, away from the easy axis, resulting in a noncollinear magnetic structure. The canting corresponds to an additional "weak" antiferromagnetic order parameter whose orientation is determined by the polar structural distortion and can be reversed by switching the ferroelectric polarization with an electric field. Our results point the way to a more general coupling mechanism between structural distortions and magnetic order parameters in magnetoelectric …
We report on structural, magnetic, electrical, and thermodynamic properties of Gd-doped LaMnO3 single crystals for Gd doping levels 0 <= x <= 1. At room temperature, for all doping levels the orthorhombic O' phase is indicative for a strong Jahn-Teller distortion. All compositions are insulating. The magnetism of La$_{1-x}$Gd$_x$MnO$_3$ is dominated by the relatively strong Mn-Mn exchange. The weakening of the antiferromagnetic interactions due to the significant decrease f the Mn-O-Mn bond angles leads to the continuous suppression of the magnetic phase-transition temperatures into the antife…
We studied structural and magnetic properties of a series of insulating double perovskite compounds, La$_{2-x}$Sr$_{x}$CuRuO$_{6}$ (0 $\le$ x $\le$ 1), representing doping via \textit{A}-site substitution. The end members La$_{2}$CuRuO$_{6}$ and LaSrCuRuO$_{6}$ form in monoclinic structure while the intermediate Sr doped compounds stabilise in triclinic structure. The Cu and Ru ions sit on alternate B-sites of the perovskite lattice with $\sim$15% anti-site defects in the undoped sample while the Sr doped samples show a tendency to higher ordering at B-sites. The undoped (x = 0) compound shows…
We report the synthesis and properties of a new layered tetragonal ternary compound CsMn$_4$As$_3$ (structure: KCu$_4$S$_3$-type, space group: $P4/mmm$, No. 123 and $Z = 2$). The material is a small band-gap semiconductor and exhibits an antiferromagnetic ground state associated with Mn spins. The compound exhibits a signature of a distinct magnetic moment canting event at 150(5)~K with a canting angle of $\approx 0.3^{\circ}$. Although, some features of the magnetic characteristics of this new compound are qualitatively similar to those of the related BaMn$_2$As$_2$, the underlying Mn sublatt…
We present a thorough $^{77}$Se NMR study of a single crystal of the magnetoelectric compound Cu$_2$OSeO$_3$. The temperature dependence of the local electronic moments extracted from the NMR data is fully consistent with a magnetic phase transition from the high-T paramagnetic phase to a low-T ferrimagnetic state with 3/4 of the Cu$^{2+}$ ions aligned parallel and 1/4 aligned antiparallel to the applied field of 14.09 T. The transition to this 3up-1down magnetic state is not accompanied by any splitting of the NMR lines or any abrupt modification in their broadening, hence there is no observa…
We demonstrate that delta-doping can be used to create a dimensionally confined region of metallic ferromagnetism in an antiferromagnetic (AF) manganite host, without introducing any explicit disorder due to dopants or frustration of spins. Delta-doped carriers are inserted into a manganite superlattice (SL) by a digital-synthesis technique. Theoretical consideration of these additional carriers show that they cause a local enhancement of ferromagnetic (F) double-exchange with respect to AF superexchange, resulting in local canting of the AF spins. This leads to a highly modulated magnetizatio…
We report the results of neutron scattering on a powder sample of Gd3Ga5O12 at high magnetic fields. We find that in high fields (B>1.8 T) the system is not fully polarized, but has a small canting of the moments induced by the dipolar interaction. We show that the degree of canting is accurately predicted by the standard Hamiltonian which includes the dipolar interaction. The inelastic scattering is dominated at large momentum transfers by a band of almost dispersionless excitations. We show that these correspond to the spin waves localized on ten site rings, expected for a system described b…
The Cu spin magnetism in La2-x-yEuySrxCuO4 (x<=0.17; y<=0.2) has been studied by means of magnetization measurements up to 14 T. Our results clearly show that in the antiferromagnetic phase Dzyaloshinsky-Moriya (DM)superexchange causes Cu spin canting not only in the LTO phase but also in the LTLO and LTT phases. In La1.8Eu0.2CuO4 the canted DM-moment is about 50% larger than in pure La2CuO4 which we attribute to the larger octahedral tilt angle. We also find clear evidence that the size of the DM-moment does not change significantly at the structural transition at T_LT from LTO to LTLO and LT…
Exchange bias is usually rationalized invoking spin pinning effects caused by uncompensated antiferromagnetic interfaces. However, for compensated antiferromagnets other extrinsic factors, such as interface roughness or spin canting, have to be considered to produce a small uncompensation. As an alternative, here we propose two (related) possible mechanisms, driven by the intrinsic Dzyaloshinskii-Moriya interaction and ferroelectric polarization, for the explanation of exchange bias effects in perovskites with compensated G-type antiferromagnetism. One of the mechanisms is only active when a m…
The ground state properties of the high spin Heisenberg chains with alternating single site anisotropy are investigated by means of the numerical exact daigonaization and DMRG method. It is found that the ferrimagnetic state appears between the Haldane phase and period doubled Néel phase for the integer spin chains. On the other hand, the transition from the Tomonaga-Luttinger liquid state into the ferrimagnetic state takes place for the half-odd-integer spin chains. In the ferrimagnetic phase, the spontaneous magnetization varies continuously with the modulation amplitude of the single site a…
We report the presence of giant spontaneous exchange bias (HSEB) in a hard and soft antiferromagnetic composite of BiFeO3-TbMnO3 (BFO-TMO in 7:3 and 8:2 ratio). The HSEB varies between 5-778Oe, but persists up to room temperature with a maximum near a spin reorientation transition temperature observed from magnetization vs. temperature measurement in Zero-field cooled (ZFC) and Field cooled (FC) modes. Isothermal remnant magnetization measurements at room temperature indicate the presence of an interfacial layer of a 2 dimensional dilute antiferromagnet in a field (2D DAFF). A stable value of …
We report on the magnetocrystalline anisotropy energy (MAE) and spin reorientation in antiferromagnetic state of spin $S=1/2$ tetramer system SeCuO$_3$ observed in torque magnetometry measurements in magnetic fields $H<5$~T and simulated using density functional calculations. We employ simple phenomenological model of spin reorientation in finite magnetic field to describe our experimental torque data. Our results strongly support collinear model for magnetic structure in zero field with possibility of only very weak canting. Torque measurements also indicate that, contrary to what is expected…
The low-energy structure and the thermodynamic properties of ferrimagnetic Heisenberg chains of alternating spins $S$ and $s$ are investigated by the use of numerical tools as well as the spin-wave theory. The elementary excitations are calculated through an efficient quantum Monte Carlo technique featuring imaginary-time correlation functions and are characterized in terms of interacting spin waves. The thermal behavior is analyzed with particular emphasis on its ferromagnetic and antiferromagnetic dual aspect. The extensive numerical and analytic calculations lead to the classification of th…
We report an experimental investigation of the two-dimensional ${J}_{\rm eff}$ = 1/2 antiferromagnetic Mott insulator by varying the interlayer exchange coupling in [(SrIrO$_3$)$_1$, (SrTiO$_3$)$_m$] ($m$ = 1, 2 and 3) superlattices. Although all samples exhibited an insulating ground state with long-range magnetic order, temperature-dependent resistivity measurements showed a stronger insulating behavior in the $m$ = 2 and $m$ = 3 samples than the $m$ = 1 sample which displayed a clear kink at the magnetic transition. This difference indicates that the blocking effect of the excessive SrTiO$_…
We investigate the antiferromagnetic canting instability of the spin-1/2 kagome ferromagnet, as realized in the layered cuprates Cu$_3$Bi(SeO$_3)_2$O$_2$X (X=Br, Cl, and I). While the local canting can be explained in terms of competing exchange interactions, the direction of the ferrimagnetic order parameter fluctuates strongly even at short distances on account of frustration which gives rise to an infinite ground state degeneracy at the classical level. In analogy with the kagome antiferromagnet, the accidental degeneracy is fully lifted only by non-linear 1/S corrections, rendering the sel…
We performed a first-principles study of the structural, vibrational, electronic and magnetic properties of NaMnF3 under applied isotropic pressure. We found that NaMnF3 undergoes a reconstructive phase transition at 8 GPa from the Pnma distorted perovskite structure toward the Cmcm post-perovskite structure. This is confirmed by a sudden change of the Mn-F-Mn bondings where the crystal goes from corner shared octahedra in the Pnma phase to edge shared octahedra in the Cmcm phase. The magnetic ordering also changes from a G-type antiferromagnetic ordering in the Pnma phase to a C-type antiferr…
Ni2SiO4, Liebenbergite, is an example of a quasi-one-dimensional magnet made up of frustrated corner sharing triangles of Ni2+ (S = 1) ions that propagate parallel to the b axis. Ni2SiO4 is isostructural with olivine, a common mineral of varying composition Fe2-xMgxSiO4, and is described in the orthorhombic space group Pnma. A synthetic polycrystalline sample of Ni2SiO4 was studied using constant wavelength powder neutron diffraction. Diffraction spectra were collected above and below the antiferromagnetic ordering transition (TN ~ 34 K) and were used to refine the atomic and magnetic structur…
We present a microscopic theory of carrier-induced ferrimagnetism in metallic double perovskite compounds such as ${\rm Sr}_{2}{\rm FeMoO}_{6}$ and ${\rm Sr}_{2}{\rm FeReO}_{6}$ which have recently attracted intense interest for their possible applications to magnetotransport devices. The theory is based on an effective "Kondo-like" Hamiltonian treated here within the large-$S$ expansion. We find that depending on the value of the carrier density the ground state is either a ferrimagnet or a layered antiferromagnet. The ferrimagnetic state has a robust half-metallic electronic structure. The t…
We use exact diagonalization combined with mean-field theory to investigate the phase diagram of the spin-orbital model for cubic vanadates. The spin-orbit coupling competes with Hund's exchange and triggers a novel phase, with the ordering of $t_{2g}$ orbital magnetic moments stabilized by the tilting of VO$_6$ octahedra. It explains qualitatively spin canting and reduction of magnetization observed in YVO$_3$. At finite temperature an orbital Peierls instability in the $C$-type antiferromagnetic phase induces modulation of magnetic exchange constants even in absence of lattice distortions. T…
We prepared a powder sample of edwardsite Cd2Cu3(SO4)2(OH)6 4H2O, which is a new candidate compound for the spin-1/2 kagome antiferromagnet, and studied its magnetic properties by magnetic susceptibility and heat capacity measurements. Edwardsite has a deformed kagome lattice with an average antiferromagnetic interaction of 51 K between nearby spins and shows an antiferromagnetic order accompanied by a small ferromagnetic moment below 4.3 K. The weak ferromagnetism is likely due to spin canting caused by sizable Dzyaloshinsky-Moriya interactions, which may stabilize the long-range magnetic ord…
By revealing an underlying relation between the Dzyaloshinskii-Moriya interaction (DMI) and the scalar spin chirality, we develop the theory of magnon thermal Hall effects in antiferromagnetic systems. The dynamic fluctuation of the scalar chirality is shown to directly respond to the nontrivial topology of magnon bands. In materials such as the jarosites compounds KFe$_3$(OH)$_6$(SO$_4$)$_2$ and veseignite BaCu$_3$V$_2$O$_8$(OH)$_2$ in the presence of in-plane DMI, the time-reversal symmetry can be broken by the fluctuations of scalar chirality even in the case of coplanar $\mathbf{q}=0$ magn…
The quaternary Heusler compound NiFeTiSn can be considered to be derived from the exotic pseudogap-compound Fe2TiSn by the replacement of one Fe atom by Ni. In contrast to Fe2TiSn, which shows a disorder-induced ferromagnetic phase, the ground state of NiFeTiSn is antiferromagnetic with the signature of spin canting. Interestingly, NiFeTiSn shows a Griffiths-like phase characterized by isolated ferromagnetic clusters before attaining the antiferromagnetic state. The Griffiths-like phase is possibly associated with the antisite disorder between Fe and Ti sites as evident from our powder X-ray d…
On-demand spin orientation with long polarized lifetime and easily detectable signal is an ultimate goal for spintronics. However, there still exists a trade-off between controllability and stability of spin polarization, awaiting a significant breakthrough. Here, we demonstrate switchable optomagnet effects in (Fe$_{1-x}$Zn$_{x}$)$_{2}$Mo$_{3}$O$_{8}$, from which we can obtain tunable magnetization, spanning from -40$\%$ to 40$\%$ of a saturated magnetization that is created from zero magnetization in the antiferromagnetic state without magnetic fields. It is accomplishable via utilizing circ…
Detailed behavior of the magnetoresistance (MR) is studied in lightly doped antiferromagnetic La_{1.99}Sr_{0.01}CuO_{4}, where, thanks to the weak ferromagnetic moment due to spin canting, the antiferromagnetic (AF) domain structure can be manipulated by the magnetic field. The MR behavior demonstrates that CuO_2 planes indeed contain anti-phase AF domain boundaries in which charges are confined, forming anti-phase stripes. The data suggest that a high magnetic field turns the anti-phase stripes into in-phase stripes, and the latter appear to give better conduction than the former, which chall…
EuMnSb$_2$ is a candidate topological material which can be tuned towards a Weyl semimetal, but there are differing reports for its antiferromagnetic (AFM) phases. The coupling of bands dominated by pure Sb layers hosting topological fermions to Mn and Eu magnetic states provides a potential path to tune the topological properties. We present a detailed analysis of the magnetic structure on three AFM phases based on single-crystal neutron diffraction, magnetization, and heat capacity data as well as polycrystalline $^{151}$Eu Mössbauer data. The Mn magnetic sublattice orders into a C-type AFM …
GHz non-reciprocal optical conductivity in hematite ($α$-$\text{Fe}_2\text{O}_3$)
Technical University of Munich（慕尼黑工业大学）；TUM School of Natural Sciences（TUM自然科学学院）；Physics Department（物理系）；Institut für Theoretische Physik, Goethe-Universität Frankfurt（法兰克福歌德大学理论物理研究所）；Institut für Festkörpertheorie（固体理论研究所）；Wilhelm-Klemm-Straße 10（威廉-克莱姆大街10号）；Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften（巴伐利亚科学院瓦尔特·迈斯纳研究所）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）；Walter Schottky Institute（瓦尔特·肖特基研究所）
A systematic study using neutron diffraction and magnetic susceptibility are reported on Mn substituted ferrimagnetic inverse spinel Ti$_{1-x}$Mn$_{x}$Co$_2$O$_4$ in the temperature interval 1.6 K $\leq$ $T$ $\leq$ 300 K. Our neutron diffraction study reveals cooperative distortions of the $T$O$_6$ octahedral for all the Jahn-Teller active ions $T$ = Mn$^{3+}$, Ti$^{3+}$ and Co$^{3+}$, which are confirmed by the X-ray photoelectron spectroscopy. Two specific compositions ($x$ = 0.2 and 0.4) have been chosen because of their unique features: noncollinear Yafet-Kittel type ordering, and weak tet…
Including the orbital off-diagonal spin and charge condensates in the self consistent determination of magnetic order within a realistic three-orbital model for the $4d^4$ compound $\rm Ca_2 Ru O_4$, reveals a host of novel features including strong and anisotropic spin-orbit coupling (SOC) renormalization, coupling of strong orbital magnetic moments to orbital fields, and a magnetic reorientation transition. Highlighting the rich interplay between orbital geometry and overlap, spin-orbit coupling, Coulomb interactions, tetragonal distortion, and staggered octahedral tilting and rotation, our …
Signatures of unconventional magnetism in the layered metallic ferromagnet LaCrSb$_3$ from ferromagnetic resonance spectroscopy
Leibniz Institute for Solid State and Materials Research Dresden（德累斯顿莱布尼茨固体与材料研究所）；TU Dresden（德累斯顿工业大学）；Indian Institute of Science Education and Research, Thiruvananthapuram（印度科学教育与研究学院，特鲁万南普拉姆）
