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Showing papers on "Antiferromagnetism published in 2022"


Journal ArticleDOI
TL;DR: The theoretical and experimental progress achieved in the field of magnetic topological materials has been reviewed in this article , with the theoretical prediction of the Quantum Anomalous Hall Effect without Landau levels, leading to the recent discoveries of magnetic Weyl semimetals and antiferromagnetic topological insulators.
Abstract: Magnetic topological materials represent a class of compounds whose properties are strongly influenced by the topology of the electronic wavefunctions coupled with the magnetic spin configuration. Such materials can support chiral electronic channels of perfect conduction, and can be used for an array of applications from information storage and control to dissipationless spin and charge transport. Here, we review the theoretical and experimental progress achieved in the field of magnetic topological materials beginning with the theoretical prediction of the Quantum Anomalous Hall Effect without Landau levels, and leading to the recent discoveries of magnetic Weyl semimetals and antiferromagnetic topological insulators. We outline the recent theoretical progress that resulted in the tabulation, for the first time, of all magnetic symmetry group representations and topology. We describe several experiments realizing Chern insulators, Weyl and Dirac magnetic semimetals, and an array of axionic and higher-order topological phases of matter as well as survey future perspectives.

105 citations


Journal ArticleDOI
TL;DR: In this paper , a combined theoretical and experimental investigation of the crystal structure together with the magnetic properties, magnetic phase transition (MPT) and magnetocaloric (MC) effects of magnetic solids have been realized to be a promising energy efficiency and environmentally friendly technology.

82 citations


Journal ArticleDOI
TL;DR: In this paper , the authors combined experimental and theoretical investigations on the magnetic properties, magnetic phase transition, and magnetocaloric effect-based solid-state magnetic refrigeration (MR) technology has been recognized as an alternative novel method to the presently commercialized gas compression technology.
Abstract: The magnetocaloric (MC) effect-based solid-state magnetic refrigeration (MR) technology has been recognized as an alternative novel method to the presently commercialized gas compression technology. Searching for suitable candidates with promising MC performances is one of the most urgent tasks. Herein, combined experimental and theoretical investigations on the magnetic properties, magnetic phase transition, and cryogenic MC performances of GdFe2Si2 have been performed. An unstable antiferromagnetic (AFM) interaction in the ground state has been confirmed in GdFe2Si2. Moreover, a huge reversible cryogenic MC effect and promising MC performances in GdFe2Si2 have been observed. The maximum isothermal magnetic entropy change, temperature-averaged entropy change with 2 K lift, and refrigerant capacity for GdFe2Si2 were 30.01 J kg−1 K−1, 29.37 J kg−1 K−1, and 328.45 J kg−1 at around 8.6 K with the magnetic change of 0–7 T, respectively. Evidently, the values of these MC parameters for the present AFM compound GdFe2Si2 are superior to those of most recently reported rare-earth-based MC materials, suggesting the potential application for active cryogenic MR.

73 citations


Journal ArticleDOI
TL;DR: In this paper , the antiferromagnetic (AFM) ordered phase of kagome lattice FeGe was shown to have a charge density wave (CDW) at wavevectors identical to that of AV3Sb5.
Abstract: A hallmark of strongly correlated quantum materials is the rich phase diagram resulting from competing and intertwined phases with nearly degenerate ground-state energies1,2. A well-known example is the copper oxides, in which a charge density wave (CDW) is ordered well above and strongly coupled to the magnetic order to form spin-charge-separated stripes that compete with superconductivity1,2. Recently, such rich phase diagrams have also been shown in correlated topological materials. In 2D kagome lattice metals consisting of corner-sharing triangles, the geometry of the lattice can produce flat bands with localized electrons3,4, non-trivial topology5–7, chiral magnetic order8,9, superconductivity and CDW order10–15. Although CDW has been found in weakly electron-correlated non-magnetic AV3Sb5 (A = K, Rb, Cs)10–15, it has not yet been observed in correlated magnetic-ordered kagome lattice metals4,16–21. Here we report the discovery of CDW in the antiferromagnetic (AFM) ordered phase of kagome lattice FeGe (refs. 16–19). The CDW in FeGe occurs at wavevectors identical to that of AV3Sb5 (refs. 10–15), enhances the AFM ordered moment and induces an emergent anomalous Hall effect22,23. Our findings suggest that CDW in FeGe arises from the combination of electron-correlations-driven AFM order and van Hove singularities (vHSs)-driven instability possibly associated with a chiral flux phase24–28, in stark contrast to strongly correlated copper oxides1,2 and nickelates29–31, in which the CDW precedes or accompanies the magnetic order. Analysis of the antiferromagnetic ordered phase of kagome lattice FeGe suggests that charge density wave is the result of a combination of electronic-correlations-driven antiferromagnetic order and instability driven by van Hove singularities.

48 citations


Journal ArticleDOI
TL;DR: In this article , a series of high quality rare earths (RE) based magnetic materials have been fabricated and a combination of theoretical and experimental investigation has been performed in terms of the crystal structure, electronic structure, magnetic properties and magnetic phase transition (MPT) as well as the magnetocaloric (MC) effect has been extensively investigated in various magnetic materials.

48 citations


Journal ArticleDOI
TL;DR: In this article , two new Co-CPs were designed and synthesized by modulating the concentration of cobalt ions, namely [Co3(HL)2(4,4′-bibp)3(H2O)4]n (1) and [Co9(L)4( 4,4,5,6)-connected topology.

35 citations


Journal ArticleDOI
TL;DR: In this article , a series of superconducting infinite-layer nickelates was studied and the intrinsic magnetic ground state arising from local moments on the nickel sublattice was observed.
Abstract: The discovery of superconductivity in Nd0.8Sr0.2NiO2 (ref. 1) introduced a new family of layered nickelate superconductors that has now been extended to include a range of strontium doping2,3, praseodymium or lanthanum in place of neodymium4–7, and the five-layer compound Nd6Ni5O12 (ref. 8). A number of studies have indicated that electron correlations are strong in these materials9–15, a feature that often leads to the emergence of magnetism. Here we report muon spin rotation/relaxation studies of a series of superconducting infinite-layer nickelates. Regardless of the rare earth ion or doping, we observe an intrinsic magnetic ground state arising from local moments on the nickel sublattice. The coexistence of magnetism—which is likely to be antiferromagnetic and short-range ordered—with superconductivity is reminiscent of some iron pnictides16 and heavy fermion compounds17, and qualitatively distinct from the doped cuprates18. Measurements of four different infinite-layer nickelates show that magnetic behaviour coexists with superconductivity. This is different from what is seen in cuprates, giving a strong distinction between the two classes of oxide superconductors.

33 citations



Journal ArticleDOI
TL;DR: In this paper, four new binary complexes with 2-carboxyphenoxyacetic acid ligand (2-H2cpa) have been successfully prepared and systematically characterized.

27 citations


Journal ArticleDOI
TL;DR: In this paper , four new binary complexes with 2-carboxyphenoxyacetic acid ligand (2-H2cpa) have been successfully prepared and systematically characterized.

27 citations


Journal ArticleDOI
TL;DR: In this paper , the surface crystalline and electronic structures of the antiferromagnetic topological insulator MnBi 2 Te 4 using scanning tunneling microscopy/spectroscopy (STM/S), micro( μ )-laser angle-resolved photoemission spectroscopy, and density functional theory calculations were analyzed.
Abstract: Abstract We study the surface crystalline and electronic structures of the antiferromagnetic topological insulator MnBi 2 Te 4 using scanning tunneling microscopy/spectroscopy (STM/S), micro( μ )-laser angle-resolved photoemission spectroscopy (ARPES), and density functional theory calculations. Our STM images reveal native point defects at the surface that we identify as Bi Te antisites and Mn Bi substitutions. Bulk X-ray diffraction further evidences the presence of the Mn-Bi intermixing. Overall, our characterizations suggest that the defects concentration is nonuniform within crystals and differs from sample to sample. Consistently, the ARPES and STS experiments reveal that the Dirac point gap of the topological surface state is different for different samples and sample cleavages, respectively. Our calculations show that the antiparallel alignment of the Mn Bi moments with respect to those of the Mn layer can indeed cause a strong reduction of the Dirac point gap size. The present study provides important insights into a highly debated issue of the MnBi 2 Te 4 Dirac point gap.

Journal ArticleDOI
TL;DR: In this article , the authors used lithium-6 atoms in an optical tweezer array to realize an eight-site Fermi-Hubbard chain near half filling and achieved single site detection by combining the two-user array with a quantum gas microscope.
Abstract: We use lithium-6 atoms in an optical tweezer array to realize an eight-site Fermi-Hubbard chain near half filling. We achieve single site detection by combining the tweezer array with a quantum gas microscope. By reducing disorder in the energy offsets to less than the tunneling energy, we observe Mott insulators with strong antiferromagnetic correlations. The measured spin correlations allow us to put an upper bound on the entropy of 0.26(4)k_{B} per atom, comparable to the lowest entropies achieved with optical lattices. Additionally, we establish the flexibility of the tweezer platform by initializing atoms on one tweezer and observing tunneling dynamics across the array for uniform and staggered 1D geometries.

Journal ArticleDOI
TL;DR: In this article , the authors show that the Chern insulator state with Chern number C = 1 appears as the AFM to canted-antiferromagnetic phase transition happens.
Abstract: The interplay between band topology and magnetism can give rise to exotic states of matter. For example, magnetically doped topological insulators can realize a Chern insulator that exhibits quantized Hall resistance at zero magnetic field. While prior works have focused on ferromagnetic systems, little is known about band topology and its manipulation in antiferromagnets. Here, we report that MnBi2Te4 is a rare platform for realizing a canted-antiferromagnetic (cAFM) Chern insulator with electrical control. We show that the Chern insulator state with Chern number C = 1 appears as the AFM to canted-AFM phase transition happens. The Chern insulator state is further confirmed by observing the unusual transition of the C = 1 state in the cAFM phase to the C = 2 orbital quantum Hall states in the magnetic field induced ferromagnetic phase. Near the cAFM-AFM phase boundary, we show that the dissipationless chiral edge transport can be toggled on and off by applying an electric field alone. We attribute this switching effect to the electrical field tuning of the exchange gap alignment between the top and bottom surfaces. Our work paves the way for future studies on topological cAFM spintronics and facilitates the development of proof-of-concept Chern insulator devices.

Journal ArticleDOI
TL;DR: In this article , a quasi-1D spin chain with antiferromagnetic and ferrotoroid properties has been proposed, which can be considered as a starting point for further exploration of the physics and applications of spin chain.
Abstract: The search of novel quasi one-dimensional (1D) materials is one of the important aspects in the field of material science. Toroidal moment, the order parameter of ferrotoroidic order, can be generated by a head-to-tail configuration of magnetic moment. It has been theoretically proposed that one-dimensional (1D) dimerized and antiferromagnetic-like spin chain hosts ferrotoroidicity and has the toroidal moment composed of only two antiparallel spins. Here, we report a ferrotoroidic candidate of Ba6 Cr2 S10 with such a theoretical model of spin chain. The structure consists of unique dimerized face-sharing CrS6 octahedral chains along the c axis. An antiferromagnetic-like ordering at ∼10 K breaks both space- and time-reversal symmetries and the magnetic point group of mm"2" allows three ferroic orders in Ba6 Cr2 S10 : (anti)ferromagnetic, ferroelectric and ferrotoroidic orders. Our investigation reveals that Ba6 Cr2 S10 is a rare ferrotoroidic candidate with quasi 1D spin chain, which can be considered as a starting point for the further exploration of the physics and applications of ferrotoroidicity. This article is protected by copyright. All rights reserved.

Journal ArticleDOI
TL;DR: The van-der-Waals material CrSBr as mentioned in this paper undergoes a transition to an A-type antiferromagnetic state with a pronounced two-dimensional character, preceded by ferromagnetic correlations within the monolayers.
Abstract: The van-der-Waals material CrSBr stands out as a promising two-dimensional magnet. Here, we report on its detailed magnetic and structural characteristics. We evidence that it undergoes a transition to an A-type antiferromagnetic state below TN ≈ 140 K with a pronounced two-dimensional character, preceded by ferromagnetic correlations within the monolayers. Furthermore, we unravel the low-temperature hidden-order within the long-range magnetically-ordered state. We find that it is associated to a slowing down of the magnetic fluctuations, accompanied by a continuous reorientation of the internal field. These take place upon cooling below Ts ≈ 100 K, until a spin freezing process occurs at T* ≈ 40 K. We argue this complex behavior to reflect a crossover driven by the in-plane uniaxial anisotropy, which is ultimately caused by its mixed-anion character. Our findings reinforce CrSBr as an important candidate for devices in the emergent field of two-dimensional magnetic materials.

Journal ArticleDOI
TL;DR: In this article , 2D van der Waals transition metal oxyhalides with low symmetry, novel magnetism, and good stability provide a versatile platform for conducting fundamental research and developing spintronics.
Abstract: 2D van der Waals (vdW) transition‐metal oxyhalides with low symmetry, novel magnetism, and good stability provide a versatile platform for conducting fundamental research and developing spintronics. Antiferromagnetic FeOCl has attracted significant interest owing to its unique semiconductor properties and relatively high Néel temperature. Herein, good‐quality centimeter‐scale FeOCl single crystals are controllably synthesized using the universal temperature‐oscillation chemical vapor transport (TO‐CVT) method. The crystal structure, bandgap, and anisotropic behavior of the 2D FeOCl are explored in detail. The absorption spectrum and electrical measurements reveal that 2D FeOCl is a semiconductor with an optical bandgap of ≈2.1 eV and a resistivity of ≈10−1 Ω m at 295 K, and the bandgap increases with decreasing thickness. Strong in‐plane optical and electrical anisotropies are observed in 2D FeOCl flakes, and the maximum resistance anisotropic ratio reaches 2.66 at 295 K. Additionally, the lattice vibration modes are studied through temperature‐dependent Raman spectra and first‐principles density functional calculations. A significant decrease in the Raman frequencies below the Néel temperature is observed, which results from the strong spin−phonon coupling effect in 2D FeOCl. This study provides a high‐quality low‐symmetry vdW magnetic candidate for miniaturized spintronics.

Journal ArticleDOI
TL;DR: In this article , the authors present experimental evidence that pairs of magnetically split hole-and electron-like Fermi arcs emerge below the Neel temperature, in the antiferromagnetic (AFM) state of cubic NdBi due to a novel band splitting effect.
Abstract: The Fermi arcs are signatures of exotic states in solids because they defy conventional concept of Fermi surfaces as closed contours in momentum space. Fermi arcs were first discovered in cuprates, and caused by the pseudogap. Weyl semimetals provided another way to generate Fermi arcs by breaking either the time reversal symmetry (TRS) or inversion symmetry of a 3D Dirac semimetal, which can result in a Weyl semimetal with pairs of Weyl nodes that have opposite chirality. The bulk-boundary correspondence associated with the Chern number leads to the emergence of Fermi arcs on the boundary. Here, we present experimental evidence that pairs of magnetically split hole- and electron-like Fermi arcs emerge below the Neel temperature, in the antiferromagnetic (AFM) state of cubic NdBi due to a novel band splitting effect. Whereas TRS is broken by the AFM order, both inversion and nonsymmorphic TRS are preserved in the bulk, precluding the possibility of a Weyl semimetal. The observed magnetic splitting is highly unusual, as it creates bands of opposing curvature, that changes with temperature and follows the antiferromagnetic order parameter. This is completely different from previously reported cases of magnetic splittings such as traditional Zeeman and Rashba, where the curvature of the bands is preserved. Therefore, our finding represents a new Fermionic state created by new type of magnetic band splitting in the presence of a long-range AFM order that are not readily explained by existing theoretical ideas.

Journal ArticleDOI
TL;DR: In this article , the frequency-dependent peaks of the AC magnetic susceptibility, along with remarkable memory effects, characterize spin-glass states, and various phenomenological parameters via different spin glass models show strong similarity within these three compounds as well as with other rare-earth metal nickelates.
Abstract: Motivated by the recent discovery of superconductivity in infinite-layer nickelate thin films, we report on a synthesis and magnetization study on bulk samples of the parent compounds ${R}$NiO$_{2}$ (${R}$=La, Pr, Nd). The frequency-dependent peaks of the AC magnetic susceptibility, along with remarkable memory effects, characterize spin-glass states. Furthermore, various phenomenological parameters via different spin glass models show strong similarity within these three compounds as well as with other rare-earth metal nickelates. The universal spin-glass behaviour distinguishes the nickelates from the parent compound CaCuO$_{2}$ of cuprate superconductors, which has the same crystal structure and $d^9$ electronic configuration but undergoes a long-range antiferromagnetic order. Our investigations may indicate a distinctly different nature of magnetism and superconductivity in the bulk nickelates than in the cuprates.

Journal ArticleDOI
TL;DR: In this article , a machine learning-based strategy was proposed to predict and understand magnetic ordering in 2D materials using a random forest and the Shapley additive explanation method with material maps defined by atomic features predicting the magnetic ordering (ferromagnetic or antiferromagnetic).
Abstract: Magnetic materials have been applied in a large variety of technologies, from data storage to quantum devices. The development of two-dimensional (2D) materials has opened new arenas for magnetic compounds, even when classical theories discourage their examination. Here we propose a machine-learning-based strategy to predict and understand magnetic ordering in 2D materials. This strategy couples the prediction of the existence of magnetism in 2D materials using a random forest and the Shapley additive explanations method with material maps defined by atomic features predicting the magnetic ordering (ferromagnetic or antiferromagnetic). While the random forest model predicts magnetism with an accuracy of 86%, the material maps obtained by the sure independence screening and sparsifying method have an accuracy of ∼90% in predicting the magnetic ordering. Our model indicates that 3d transition metals, halides, and structural clusters with regular transition-metal sublattices have a positive contribution in the total weight deciding the existence of magnetism in 2D compounds. This behavior is associated with the competition between crystal field and exchange splitting. The machine learning model also indicates that the atomic spin orbit coupling (SOC) is a determinant feature for the identification of the patterns separating ferro- from antiferromagnetic order. The proposed strategy is used to identify novel 2D magnetic compounds that, together with the fundamental trends in the chemical and structural space, pave novel routes for experimental exploration.

Journal ArticleDOI
TL;DR: In this paper , a family of 2D magnets with P4m2 symmetry-protected anisotropic DMI was proposed and demonstrated, and various topological spin configurations, including FM/AFM antiskyrmion and AFM vortex-antivortex pair, emerged in this family.
Abstract: As a fundamental magnetic parameter, Dzyaloshinskii-Moriya interaction (DMI), has gained a great deal of attention in the last two decades due to its critical role in formation of magnetic skyrmions. Recent discoveries of two-dimensional (2D) van der Waals (vdW) magnets has also gained a great deal of attention due to appealing physical properties, such as gate tunability, flexibility, and miniaturization. Intensive studies have shown that isotropic DMI stabilizes ferromagnetic (FM) topological spin textures in 2D magnets or their corresponding heterostructures. However, the investigation of anisotropic DMI and antiferromagnetic (AFM) topological spin configurations remains elusive. Here, we propose and demonstrate a family of 2D magnets with P4m2 symmetry-protected anisotropic DMI. More interestingly, various topological spin configurations, including FM/AFM antiskyrmion and AFM vortex-antivortex pair, emerge in this family. These results give a general method to design anisotropic DMI and pave the way toward topological magnetism in 2D materials using crystal symmetry.

Journal ArticleDOI
TL;DR: In this paper , the spin splitting torque (SST) was theoretically predicted, which combines advantages of conventional spin transfer torque and spin-orbit torque as well as enables controllable spin polarization.
Abstract: Current-induced spin torques provide efficient data writing approaches for magnetic memories. Recently, the spin splitting torque (SST) was theoretically predicted, which combines advantages of conventional spin transfer torque (STT) and spin-orbit torque (SOT) as well as enables controllable spin polarization. Here we provide the experimental evidence of SST in collinear antiferromagnet RuO_{2} films. The spin current direction is found to be correlated to the crystal orientation of RuO_{2} and the spin polarization direction is dependent on (parallel to) the Néel vector. These features are quite characteristic for the predicted SST. Our finding not only presents a new member for the spin torques besides traditional STT and SOT, but also proposes a promising spin source RuO_{2} for spintronics.

Journal ArticleDOI
TL;DR: In this article , a simple mean-field approach for frustrated antiferromagnets on hexagonal lattices, aimed to describe the high-temperature part of the temperature-magnetic field phase diagram, is proposed.
Abstract: Simple mean-field approach for frustrated antiferromagnets on hexagonal lattices, aimed to describe the high-temperature part of the temperature-magnetic field phase diagram, is proposed. It is shown, that an interplay between modulation vector symmetry, Zeeman energy and magneto-dipolar interaction leads to stabilization of the triple-$Q$ skyrmion lattice in a certain region of the phase diagram. Corresponding analytical expressions for phase boundaries are derived. It is argued that the developed theory can be applied for the description of the high-temperature part of the phase diagram observed experimentally for Gd$_2$PdSi$_3$ compound.

Journal ArticleDOI
TL;DR: In this article , a charge order (CO) in infinite-layer nickelates La1-xSrxNiO2 using resonant x-ray scattering across the Ni L-edge was uncovered.
Abstract: A defining signature of strongly correlated electronic systems is the existence of competing phases with similar ground state energies, resulting in a rich phase diagram. While in the recently discovered nickelate superconductors, a high antiferromagnetic exchange energy has been reported, which implies the existence of strong electronic correlations, signatures of competing phases have not yet been observed. Here, we uncover a charge order (CO) in infinite-layer nickelates La1-xSrxNiO2 using resonant x-ray scattering across the Ni L-edge. In the parent compound, the CO arranges along the Ni-O bond direction with an incommensurate wave vector (0.344+/-0.002, 0) r.l.u., distinct from the stripe order in other nickelates which propagates along a direction 45 degree to the Ni-O bond. The CO resonance profile indicates that CO originates from the Ni 3d states and induces a parasitic charge modulation of La electrons. Upon doping, the CO diminishes and the ordering wave vector shifts toward a commensurate value of 1/3 r.l.u., indicating that the CO likely arises from strong correlation effects and not from Fermi surface nesting.

Journal ArticleDOI
TL;DR: In this paper , the authors present experimental evidence that pairs of magnetically split hole-and electron-like Fermi arcs emerge below the Neel temperature, in the antiferromagnetic (AFM) state of cubic NdBi due to a novel band splitting effect.
Abstract: The Fermi arcs are signatures of exotic states in solids because they defy conventional concept of Fermi surfaces as closed contours in momentum space. Fermi arcs were first discovered in cuprates, and caused by the pseudogap. Weyl semimetals provided another way to generate Fermi arcs by breaking either the time reversal symmetry (TRS) or inversion symmetry of a 3D Dirac semimetal, which can result in a Weyl semimetal with pairs of Weyl nodes that have opposite chirality. The bulk-boundary correspondence associated with the Chern number leads to the emergence of Fermi arcs on the boundary. Here, we present experimental evidence that pairs of magnetically split hole- and electron-like Fermi arcs emerge below the Neel temperature, in the antiferromagnetic (AFM) state of cubic NdBi due to a novel band splitting effect. Whereas TRS is broken by the AFM order, both inversion and nonsymmorphic TRS are preserved in the bulk, precluding the possibility of a Weyl semimetal. The observed magnetic splitting is highly unusual, as it creates bands of opposing curvature, that changes with temperature and follows the antiferromagnetic order parameter. This is completely different from previously reported cases of magnetic splittings such as traditional Zeeman and Rashba, where the curvature of the bands is preserved. Therefore, our finding represents a new Fermionic state created by new type of magnetic band splitting in the presence of a long-range AFM order that are not readily explained by existing theoretical ideas.

Journal ArticleDOI
TL;DR: In this article , an out-of-plane damping-like torque can be generated in ruthenium dioxide (RuO2)/permalloy devices when the Néel vector of the collinear antiferromagnet RuO2 is canted relative to the sample plane.
Abstract: Symmetry plays a central role in determining the polarization of spin currents induced by electric fields. It also influences how these spin currents generate spin-transfer torques in magnetic devices. Here we show that an out-of-plane damping-like torque can be generated in ruthenium dioxide (RuO2)/permalloy devices when the Néel vector of the collinear antiferromagnet RuO2 is canted relative to the sample plane. By measuring characteristic changes in all three components of the electric-field-induced torque vector as a function of the angle of the electric field relative to the crystal axes, we find that the RuO2 generates a spin current with a well-defined tilted spin orientation that is approximately parallel to the Néel vector. A maximum out-of-plane damping-like spin torque efficiency per unit electric field of 7 ± 1 × 103 Ω−1 m−1 is measured at room temperature. The observed angular dependence indicates that this is an antiferromagnetic spin Hall effect with symmetries that are distinct from other mechanisms of spin-current generation reported in antiferromagnetic and ferromagnetic materials. The collinear antiferromagnet ruthenium dioxide (RuO2) can generate an electric-field-induced spin current with a well-defined tilted spin orientation that is approximately parallel to the Néel vector.

Journal ArticleDOI
TL;DR: In this article , the authors present evidence for antiferromagnetic order in the case of the nuclear quadrupole resonance spectrum at two crystallographically inequivalent As sites, which is a promising system to study how the absence of local inversion symmetry induces or influences unconventional magnetic and superconducting states.
Abstract: Spatial inversion symmetry in crystal structures is closely related to the superconducting (SC) and magnetic properties of materials. Recently, several theoretical proposals that predict various interesting phenomena caused by the breaking of the local inversion symmetry have been presented. However, experimental validation has not yet progressed owing to the lack of model materials. Here we present evidence for antiferromagnetic (AFM) order in CeRh_{2}As_{2} (SC transition temperature T_{SC}∼0.37 K), wherein the Ce site breaks the local inversion symmetry. The evidence is based on the observation of different extents of broadening of the nuclear quadrupole resonance spectrum at two crystallographically inequivalent As sites. This AFM ordering breaks the inversion symmetry of this system, resulting in the activation of an odd-parity magnetic multipole. Moreover, the onset of antiferromagnetism T_{N} within an SC phase, with T_{N}

Journal ArticleDOI
TL;DR: In this article , the authors used ultrafast spectroscopy to reveal bound states of d-orbitals and phonons in 2D vdW antiferromagnet NiPS3.
Abstract: In van der Waals (vdW) materials, strong coupling between different degrees of freedom can hybridize elementary excitations into bound states with mixed character1-3. Correctly identifying the nature and composition of these bound states is key to understanding their ground state properties and excitation spectra4,5. Here, we use ultrafast spectroscopy to reveal bound states of d-orbitals and phonons in 2D vdW antiferromagnet NiPS3. These bound states manifest themselves through equally spaced phonon replicas in frequency domain. These states are optically dark above the Néel temperature and become accessible with magnetic order. By launching this phonon and spectrally tracking its amplitude, we establish the electronic origin of bound states as localized d-d excitations. Our data directly yield electron-phonon coupling strength which exceeds the highest known value in 2D systems6. These results demonstrate NiPS3 as a platform to study strong interactions between spins, orbitals and lattice, and open pathways to coherent control of 2D magnets.

Journal ArticleDOI
TL;DR: In this article , the spin dynamics in non-collinear antiferromagnet Mn3Sn films using nitrogen-vacancy (NV) centers were investigated and the off-resonance dipole-dipole coupling between spin dynamics and proximate NV centers was demonstrated by NV relaxometry measurements.
Abstract: Novel non‐collinear antiferromagnets with spontaneous time‐reversal symmetry breaking, non‐trivial band topology, and unconventional transport properties have received immense research interest over the past decade due to their rich physics and enormous promise in technological applications. One of the central focuses in this emerging field is exploring the relationship between the microscopic magnetic structure and exotic material properties. Here, nanoscale imaging of both spin–orbit‐torque‐induced deterministic magnetic switching and chiral spin rotation in non‐collinear antiferromagnet Mn3Sn films using nitrogen‐vacancy (NV) centers are reported. Direct evidence of the off‐resonance dipole–dipole coupling between the spin dynamics in Mn3Sn and proximate NV centers is also demonstrated by NV relaxometry measurements. These results demonstrate the unique capabilities of NV centers in accessing the local information of the magnetic order and dynamics in these emergent quantum materials and suggest new opportunities for investigating the interplay between topology and magnetism in a broad range of topological magnets.

Journal ArticleDOI
TL;DR: In this article, the structural, elastic, electronic and magnetic properties of transition metals based perovskites were investigated using advanced exchange-correlation methods based on density functional theory (DFT).
Abstract: Structural, elastic, electronic and magnetic properties of the transition metals based perovskites SrTMO3 (TM = Mn, Fe, Co, Tc, Ru, Rh, Re, Os, Ir) are investigated using advanced exchange-correlation methods based on density functional theory (DFT). The calculated structural parameters are found consistent with the experiments. The elastic properties reveal that these compounds are anisotropic, mechanically stable and ductile except SrMnO3. Electronic properties show that the strong hybridization between TM-d and O-2p states at the Fermi level make these compounds metallic expect SrMnO3 which is half-metal. The electrical resistivity indicates that these compounds are good conductors at room temperature. Magnetic ordering and magnetic susceptibility show that SrMnO3, SrFeO3 and SrTcO3 are G-type antiferromagnetic; SrCoO3, SrRuO3 and SrOsO3 are ferromagnetic, whereas SrRhO3, SrReO3 and SrIrO3 are paramagnetic/non-magnetic compounds. The study also confirms that TM-3d perovskites are strongly correlated electron systems while spin-orbit coupling effect is dominant in TM-5d perovskites.

Journal ArticleDOI
TL;DR: In this paper, the exchange bias effect in Fe3GeTe2 (FGT)/CrOCl heterostructures through both anomalous Hall effect (AHE) and reflective magnetic circular dichroism (RMCD) measurements is studied.
Abstract: The exchange bias effect is extremely expected in 2D van der Waals (vdW) ferromagnetic (FM)/antiferromagnetic (AFM) heterostructures due to the high‐quality interface. CrOCl possesses strong magnetic anisotropy at 2D limit, and is an ideal antiferromagnet for constructing FM/AFM heterostructures to explore the exchange bias effect. Here, the exchange bias effect in Fe3GeTe2 (FGT)/CrOCl heterostructures through both anomalous Hall effect (AHE) and reflective magnetic circular dichroism (RMCD) measurements is studied. In the AHE measurements, the exchange bias field (HEB) at 3 K exhibits a distinct increase from ≈150 Oe to ≈450 Oe after air exposure, and such variation is attributed to the formation of an oxidized layer in FGT by analyzing the cross‐sectional microstructure. The HEB is successfully tuned by changing the FGT/CrOCl thickness and the cooling field. Furthermore, a larger HEB of ≈750 Oe at 1.7 K in FGT/CrOCl heterostructure through RMCD measurements is observed, and it is proposed that the larger HEB in RMCD measurements is related to the distribution of uncompensated spins at the interface. This work reveals several intriguing phenomena of the exchange bias effect in 2D vdW magnetic systems, which paves the way for the study of related spintronic devices.