Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session T43: Topological Antiferromagnets and Altermagnets |
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Sponsoring Units: DMP Chair: Yuhang Li, University of California, Riverside Room: Room 317 |
Thursday, March 9, 2023 11:30AM - 11:42AM |
T43.00001: Tuning of anomalous Hall effect by spin reorientation in a novel altermagnetic compound CrSb Suvadip Das, Igor I Mazin Recently, a novel phase of non-relativistic collinear magnetism (unlike ferromagnetism and anti- |
Thursday, March 9, 2023 11:42AM - 11:54AM |
T43.00002: Magneto transport and electronic properties of altermagnetic MnTe Resham B Regmi, Hari Bhandari, Peter Siegfried, Igor I Mazin, Nirmal J Ghimire In addition to the well-known ferrro(ferri)magnets (FM) and Neel antiferromagnets (AF), a new class of magnetic materials has been recently realized. They are dubbed "altermagnets" (AM), since they are (a) principally different from the two "canonical" classes, and (b) as opposed to AF, they include alternating (staggered) magnetization density not only in the real space but also in the reciprocal space. MnTe is one of the handful of materials predicted to be altermagnetic. MnTe crystalizes in NiAs- type structure in space group P6/mmm. It orders into an antiferromagnetic state at a relatively high temperature of around 310 K. the magnetic structure consists of ferromagnetic Mn planes coupled antiferromagnetically along the c-axis such that two antiferromagnetic Mn sublattices are related not by a regular 6-fold rotation, but by a 6-fold screw axis thus providing the necessary crystal symmetry that couples with the spin structure to give rise to altermagnetism. Here we will present the magnetotransport properties measured on the bulk single crystal of MnTe and discuss the results with respect to the calculated electronic band structure. |
Thursday, March 9, 2023 11:54AM - 12:06PM Author not Attending |
T43.00003: CDW induced structural symmetry breaking in Kagome metal FeGe Liran Wang, Frederic Hardy, Christoph Meingast, Xueliang Wu, Mingquan He, Yisheng Chai, Aifeng Wang Charge-ordered phases in kagome metals have garnered much recent attention owing to their highly interesting properties. Recently, CDW order within the antiferromagnetic (AFM) ordered phase of the kagome metal FeGe has attracted attention [1-4]. Here, we further investigate this compound using high-resolution dilatometry techniques. Our results suggest a symmetry breaking of the hexagonal in-plane structure at the onset of the CDW transition. Detailed heat-capacity measurements find a clear anomaly at the spin-canting phenomenon [2] slightly below the CDW transition. These results offers us an opportunity to further explore the charge order in this FeGe kagome metallic system. [1] T. Neupertet,et al. Nat. Phys. 18, 137–143 (2022) [2] X. Tenget et al. . Nature 609, 490–495 (2022) [3] J.-X. Yin, et al. Phys. Rev. Lett. 129, 166401 (2022) [4] C. Setty, et al. arXiv:2203.01930 |
Thursday, March 9, 2023 12:06PM - 12:18PM |
T43.00004: Buffer layered growth of nickeline and zinc-blende MnTe on c-plane Al2O3 Deepti Jain, Hee Taek Yi, Matthew Brahlek, Myung-Geun Han, Seongshik Oh MnTe is a well-known polymorphic semiconductor with nickeline, zinc blende and wurtzite being its most widely studied phases. While nickeline MnTe has found application in dilute magnetic semiconductors and thermoelectric materials, the zinc blende and wurtzite phases are utilized in optoelectronic devices owing to their larger bandgap. So far, these films have been grown on structurally compatible substrates, via doping or by displacive transformation. We have successfully grown both nickeline and zinc blende phases on c-plane Al2O3 substrates by developing different buffer layer for the two phases. Such control over growth of MnTe could potentially lead to novel heterostructures and provide new directions for fabrication of devices. It is also particularly beneficial from the point of view of growing thin films of Mn based magnetic topological insulators. |
Thursday, March 9, 2023 12:18PM - 12:30PM |
T43.00005: Global Ferromagnetism and Localized Dimers in (Sn0.9Mn0.1)Te FARHAN ISLAM, Santanu Pakhira, Deborah L. Schlagel, Daniel M Pajerowski, Thomas W Heitmann, David C Johnston, Robert J McQueeney, David Vaknin Neutron scattering and magnetic susceptibility experiments of the dilute magnetic topological insulator (Sn0.9Mn0.1)Te reveal long-range ferromagnetic (FM) order below TC = 12 ± 1 K. Neutron scattering data provide additional evidence for short-range magnetic correlations within the FM state. Analysis of the short-range correlations reveals competing pairwise magnetic interactions from nearest-neighbor FM Mn-Mn direct interactions, next-nearest neighbor antiferromagnetic (AFM) Mn-Te-Mn super-exchange interactions, and longer-range AFM Mn-Te-Sn-Te-Mn interactions. The AFM interaction via the linear Mn-Te-Mn bond (J ~ 0.7 meV), quantified in previous measurements of dilute Sn0.97Mn0.03Te, is nearly an order of magnitude greater than other interactions and likely supports the formation of strong Mn-Mn dimer singlet states. Such dimers would not participate in the global FM order. However, the dimer singlet spectrum cannot be resolved in our data due to the higher Mn concentration and interactions of the dimer quantum state with other Mn neighbors and the internal molecular field. |
Thursday, March 9, 2023 12:30PM - 12:42PM |
T43.00006: Engineering magnetic transition metal chalcogenide-based quantum interfaces Hang Chi Significant progress has been made in conceptualizing geometric aspects of condensed matter <!--[if supportFields]>style='mso-spacerun:yes'> ADDIN EN.CITE |
Thursday, March 9, 2023 12:42PM - 12:54PM |
T43.00007: Topological magneto-electric response in non-magnetic and anti-ferromagnetic topological insulators Perry T Mahon, Chao Lei, Allan H MacDonald The theory of magneto-electric response in topological insulators is confusing because bulk calculations yield a topologically protected non-zero result that is forbidden by time-reversal symmetry. The theoretical bulk response is expressed as an integral over three-dimensional momentum space that is quantized. This conundrum can be resolved by recognizing the importance of time-reversal symmetry breaking at the surface. Evidently in this instance the bulk theory does not fully explain the magneto-electric phenomenology of real devices, and this has created some confusion in the literature. For instance, in thin-films for which time-reversal symmetry is not broken either in the bulk or at the surface, topological insulators have no magneto-electric response. Here we consider the magneto-electric response of non-magnetic and anti-ferromagnetic multilayer crystals. We develop tight-binding Hamiltonians for both cases, which are special in the sense that the bulk magneto-electric response coefficient can be evaluated analytically in a Hamiltonian gauge. Motivated by the modern theory of magnetization, and by numerical thin-film calculations for the same model which are presented in a related talk by Lei, Mahon, and MacDonald, we compare the structures of the bulk momentum-space integrands between the two cases and discuss interior/surface decompositions of the total response. |
Thursday, March 9, 2023 12:54PM - 1:06PM |
T43.00008: Nonlinear Hall effect induced by anomalous skew scattering in PT-symmetric systems Da Ma, Arpit Arora, Giovanni Vignale, Justin Song We uncover a new mechanism of the nonlinear Hall effect in PT-symmetric systems. Although skew scattering and Berry curvature are both PT-odd, the combination of the two is PT-even, giving rise to the anomalous skew scattering nonlinear Hall effect (ASN). ASN grows with increasing relaxation time, and it diverges in the clean limit. Strikingly, we find that ASN supports a helicity dependent photocurrent even in a PT symmetric metal in contrast to all other metallic second order nonlinear photocurrents that are insensitive to helicity: this enables means to directly isolate ASN. We anticipate that accounting for ASN will provide additional tools in diagnosing the antiferromagnetic order of PT-symmetric metals. |
Thursday, March 9, 2023 1:06PM - 1:18PM |
T43.00009: Graphene Induced Colossal Magnetoresistance and Critical Behavior in Phase Segregated Iron Oxide Noah Schulz, Amit Chanda, Derick Detellem, Chang-Ming Hung, Humberto R Gutierrez, Manh-Huong Phan, Hariharan Srikanth, Gopal Datt, Tapati Sarkar, M. Venkata Kamalakar Interfacial magnetic and electronic properties in two-dimensional systems placed in proximity with magnetic substrates have been shown to exhibit exotic interfacial phenomena (Nanoscale 5, 1902-1909 (2013)). Further, bi-phase iron oxide (BPIO) consisting of a majority phase Fe3O4 and minority phase α-Fe2O3 has been shown to be a unique platform for observing the coexistence of competing magnetic phases. Here, the change in the bulk magnetic and electronic properties of 100 nm thick BPIO due to the inclusion of monolayer graphene (Gr) is explored. Magnetometry measurements indicate strong antiferromagnetic (AFM) coupling between BPIO and Gr as compared to bare BPIO via a 50% reduction in saturation magnetization. Further, magnetoresistance (MR) measurements were performed on both BPIO/Gr/Pt and BPIO/Pt. While BPIO/Pt shows negative MR throughout the temperature range, BPIO/Gr/Pt exhibits a change in the sign of MR from positive to negative below Tp = 240 K. Furthermore, unlike BPIO/Pt, BPIO/Gr/Pt shows a peak in the temperature dependent resistivity measurement which coincides with changes in the sign of MR. These results can be understood via a percolation model and competing localization and delocalization of carriers, induced by strong AFM coupling in Gr and the phase segregated nature of BPIO. |
Thursday, March 9, 2023 1:18PM - 1:30PM |
T43.00010: Field-independent transverse thermal Hall behavior in antiferromagnet YbMnBi2 Jiamin Wen, Kaustuv Manna, Yu Pan, Claudia Felser, Joseph P Heremans YbMnBi2 is a canted antiferromagnet with a Neel temperature of 290 K and the Curie temperature for spin canting is 250 K. The antiferromagnetic moments are aligned along [001] direction with spin canted along [110] direction. We report measurements of thermal Hall effect with heat flux applied along [1-10] direction, magnetic field along [110] direction, and measured transverse transport signals along [001] direction. We investigated both Nernst effect and thermal Hall effect. In the above configuration, we observed a field-independent thermal Hall conductance plateau around three halves of the thermal conductance quantum with a temperature and magnetic field range approximately from 150 K to 250 K and 1 T to 5 T. Surprisingly, the plateau disappears not only above the Curie temperature, but also at temperatures below 150 K. In the same configuration, we replaced the applied temperature gradient by a current flow and conducted electrical Hall effect measurements for the same sample: the ratio of thermal to electrical Hall effects deviates strongly from the Wiedemann-Franz law. The Nernst conductivity is also much larger in this configuration than when magnetic field is applied along [100] direction, as reported in Ref. 1. |
Thursday, March 9, 2023 1:30PM - 1:42PM |
T43.00011: Significant composition dependence of the anomalous Hall effect in the metallic triangular lattice antiferromagnet Co1/3TaS2 Pyeongjae Park, Chaebin Kim, Yeochan An, Yoon-Gu Kang, Maxim Avdeev, Romain Sibille, Kazuki Iida, Ryoichi Kajimoto, Ki Hoon Lee, Han-Jin Noh, Myung Joon Han, Cristian Batista, Je-Geun Park This presentation reports that metallic triangular antiferromagnet Co1/3TaS2 exhibits a substantial anomalous Hall effect (AHE) tunable by cobalt composition. We have synthesized single-crystal CoxTaS2 with a range of Co composition (0.299 < x < 0.34) and characterized their bulk properties. For 0.299 < x < 0.325, CoxTaS2 undergoes two antiferromagnetic phase transitions at TN1 = 38 K and TN2 = 26.5 K. It exhibits the anomalous Hall effect as large as conventional ferromagnets (σxy(H = 0) ~ 70 Ω-1 cm-1) below TN2, together with a weak ferromagnetic moment along the c-axis (Mz(H = 0) ~ 0.01μB). Surprisingly, such bulk properties vary significantly with x, even though the investigated range does not deviate much from the ideal value of x = 1/3. Most importantly, the weak ferromagnetic moment (Mz(H = 0)) and the AHE (σxy(H = 0)) are absent for x > 0.325. Based on the similar composition dependence observed in isostructural material Fe1/3NbS2 [1] and our neutron diffraction data, we discuss the origin of the tunable AHE in CoxTaS2. |
Thursday, March 9, 2023 1:42PM - 1:54PM |
T43.00012: An investigation of the magnetoelectric monopole response in Chromia Syed Qamar Abbas Shah, Ather Mahmood, Arun Parthasarathy, Allan H MacDonald, Christian Binek Powder samples have been suggested as a pathway to fabricate isotropic magnetoelectric (ME) materials which effectively only have a pseudoscalar or monopole ME response. We demonstrate that random distribution of ME grains alone does not warrant isotropic ME response because the activation of a non-vanishing ME response requires a ME field cooling protocol which tends to induce preferred axes. We investigate the evolution of ME susceptibility in powder chromia samples for various ME field cooling protocols both theoretically and experimentally. In particular, we work out the theoretical expressions for ME susceptibility for powder Chromia in the framework of statistical mechanics where Boltzmann factors weigh the orientation of the Néel vector relative to the local orientation of the c-axis of a grain. Previous approximations oversimplified the thermodynamic nature of the annealing process giving rise to misleading conclusions on the role of the magnitude of the applied product of electric and magnetic fields on the ME response. In accordance with our refined thermodynamic theory, a strong dependence of the functional form of α vs. T of Chromia powders on the ME field cooling protocol is observed. It shows on one hand that Chromia powder is not generically an isotropic ME effective medium as sometimes misleadingly stated, but, on the other hand, provides a pathway to realize the elusive isotropic ME response. |
Thursday, March 9, 2023 1:54PM - 2:06PM |
T43.00013: Nontrivial triplet band-topology in the spin gap materials, KCuCl3 and TlCuCl3 (Part 1) Charles B Walker, Matthew S Stern, Judit Romhanyi We investigate the spin gap system, XCuCl3 (X=K, Tl), where the magnetic copper ions form a 3-dimensional lattice of two inequivalent dimers. The dominant antiferromagnetic intra-dimer interaction leads to a dimer-singlet ground state. Inelastic neutron scattering[1] and electron spin resonance measurements[2] revealed dispersive triplet excitations. The spectrum has been studied using isotropic Heisenberg models, which include further neighbor exchange paths. |
Thursday, March 9, 2023 2:06PM - 2:18PM |
T43.00014: Nontrivial triplet band-topology in the spin gap materials, KCuCl3 and TlCuCl3 (Part 2) Matthew S Stern, Charles B Walker, Judit Romhanyi We investigate the spin gap system, XCuCl3 (X=K, Tl), where the magnetic copper ions form a 3D lattice of two inequivalent dimers. The dominant antiferromagnetic intra-dimer interaction leads to a dimer-singlet ground state. Inelastic neutron scattering[1] and electron spin resonance measurements[2] revealed dispersive triplet excitations. The spectrum has been studied using isotropic Heisenberg models, which include further neighbor exchange paths. |
Thursday, March 9, 2023 2:18PM - 2:30PM |
T43.00015: Structural and Magnetic Properties of EuIr3Si7 Single Crystals Binod K Rai, Boris A Maiorov, Alex Bretana, Joseph Paddison, Stuart Calder, Matthias D Frontzek, Christopher A Mizzi Recently, Eu-based intermetallic compounds have been reported to exhibit complex magnetic textures. In this talk, I will present the physical properties of a new member, the EuIr3Si7 single crystal, of the RT3M7 family. This family of compounds has already shown interesting magnetic properties such as anomalous metamagnetism in YbRh3Si7, ferromagnetic ordering along the hard axis in YbIr3Ge7, and charge-neutral fermions in YbIr3Si7. EuIr3Si7 crystallizes in the ScRh3Si7 structure type with space group R-3c. Furthermore, it exhibits two magnetic phases below TN1 = 5 K and TN2 = 15 K, with easy-axis anisotropy. The presentation discusses two magnetic phases assessed using magnetization, specific heat, ac susceptibility, and neutron diffraction data. |
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