Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session T68: Magnetotransport in Topological Materials IIFocus Recordings Available
|
Hide Abstracts |
Sponsoring Units: DMP GMAG DCMP Chair: Shafayat Hossain, Princeton University; Shirin Mozaffari, University of Tennessee Room: Hyatt Regency Hotel -Hyde Park B |
Thursday, March 17, 2022 11:30AM - 11:42AM |
T68.00001: Nonlinear Hall Effect and Magnetoresistance in EuCd2P2 Fazel Tafti Materials with strong magnetoresistive responses are the backbone of spintronic technology, magnetic sensors, and hard drives. Among them, manganese oxides with a mixed-valence and a cubic perovskite structure stand out due to their colossal magnetoresistance (CMR). A double exchange interaction underlies the CMR in manganates, whereby charge transport is enhanced when the spins on neighboring Mn3+ and Mn4+ ions are parallel. Prior efforts to find different materials or mechanisms for CMR resulted in a much smaller effect. Here an enormous CMR at low temperatures in EuCd2P2 without manganese, oxygen, mixed-valence, or cubic perovskite structure is shown. EuCd2P2 has a layered trigonal lattice and exhibits antiferromagnetic ordering at 11 K. The magnitude of CMR (104%) in as-grown crystals of EuCd2P2 rivals the magnitude in optimized thin films of manganates. The magnetization, transport, and synchrotron X-ray data suggest that strong magnetic fluctuations are responsible for this phenomenon. The realization of CMR at low temperatures without heterovalency leads to a new regime for materials and technologies related to antiferromagnetic spintronics. |
Thursday, March 17, 2022 11:42AM - 11:54AM |
T68.00002: Angle and electric field dependent electrical transport in magnetic topological insulators Christopher Eckberg, Gang Qui, Su Kong Chong, Peng Zhang, Lixuan Tai, Peng Deng, David E Graf, Kang-Lung Wang Magnetic topological matter has received significant attention as a potential building block in future spintronic and quantum computing technologies. Notably, through careful simultaneous tuning of the magnetic exchange gap and electronic band structure, these systems have been shown to exhibit novel electronic states, including the quantum anomalous Hall insulator phase. In this talk we present the electrical transport properties of a high quality magnetic topological insulator subject to magnetization rotation and electric field tuning; discussing the contributions of bulk, surface, and chiral edge states to the observed transport signatures. |
Thursday, March 17, 2022 11:54AM - 12:06PM |
T68.00003: Observation of giant anomalous Hall effect in a topological magnet Jaime M Moya, Jianwei Huang, Shiming Lei, Kevin J Allen, Ming Yi, Emilia Morosan The boom of topological materials and the novel properties which they host has generated great interest in the condensed mattered community over the last decade. An interesting research direction is coupling topological properties with strong correlations, electronic or magnetic, to design technologically useful materials. One such possibility is inducing magnetism in a Dirac semimetal, resulting in a net Berry curvature and thus a large anomalous Hall effect (AHE) response which has been proposed as a path towards energy efficient electronic and spintronic devices. Several compounds in the tetragonal BaAl4 family (space group I4/mmm), possess Dirac cones near the Fermi level, which can be tuned by chemical substitution. Furthermore, magnetism can be induced by substituting Ba with rare earth ions, providing a promising route to engineering a large AHE. |
Thursday, March 17, 2022 12:06PM - 12:18PM |
T68.00004: Unusual Magneto-transport Properties Observed in EuZn2As2 under High Magnetic Field Joanna Blawat, Smita Speer, John Singleton, Weiwei Xie, Rongying Jin For magnetic materials that belong to the type-IV magnetic space group, the nontrivial symmetry is expected to produce topological phases. Layered EuT2Pn2 (T = Zn, Cd; Pn = As, Sb) may hold such promises. While Eu forms an A-type antiferromagnetic (AFM) ordering in all of these compounds, the transition temperature for EuZn2As2 is the highest with TN = 19 K. Our magneto-transport measurements show extremely large response of the electrical resistivity to both internal and external magnetic field. We will present the temperature and magnetic field dependence of the resistivity anisotropy under various field and current configurations. By applying pulse field up to 60 T, the non-monotonic field dependence of the resistivity reflects three spin configurations corresponding to the A-type AFM (low field), ferromagnetic (intermediate field), and canted AFM states. Implications of our results will be discussed. |
Thursday, March 17, 2022 12:18PM - 12:30PM |
T68.00005: Visualizing currents in the quantum anomalous Hall regime George M Ferguson, Run Xiao, David Low, Lingjie Zhou, Anthony R Richardella, Cui-Zu Chang, Nitin Samarth, Katja Nowack We report a magnetic imaging study of the current distribution in the quantum anomalous Hall regime. We use a scanning superconducting quantum interference device (SQUID) microscope with micrometer scale spatial resolution to image the magnetic fields above Cr-doped (Bi,Sb)2Te3 samples. From these data we reconstruct the local current density, allowing us to visualize how current flows in our devices. Surprisingly, we find that most current flows in the bulk when the transport coefficients are quantized. By combining this observation with images of the equilibrium persistent currents, we construct a comprehensive picture of electronic transport in the quantum anomalous Hall regime. |
Thursday, March 17, 2022 12:30PM - 12:42PM |
T68.00006: Elucidating the physical origin for the disappearance of quantum anomalous Hall (QAHE) effect in Cr-doped (Bi,Sb)2Te3 above sub-Kelvin temperatures by transport and scanning tunneling spectroscopic (STS) studies Akiyoshi Park, Sebastien N Abadi, Adrian Llanos, Chien-Chang Chen, Marcus L Teague, Nai-Chang Yeh, Lixuan Tai, Peng Zhang, Kang Wang Experimental observation of the QAHE among Cr-doped (Bi,Sb)2Te3, which are magnetic topological insulators (MTIs), has been bound to below sub-Kelvin temperatures. Such limitation of the QAHE imposes an inherent constraint on technological applications, which is unexpected given that these MTIs exhibit long-range ferromagnetic ordering at much higher temperatures: Transport measurements of Cr-doped (Bi,Sb)2Te3 have shown bulk Curie temperatures (TC) ranging from 20 to 30 K, whereas QAHE only occurred below ~ 0.1 K. To shed light on this discrepancy, a combined study of temperature dependent transport and STS measurements in Cr-doped (Bi,Sb)2Te3 were performed. Our experimental results revealed that despite a topological gap opening in the surface state of the MTIs below TC, the presence of a bulk valence band within the similar energy range resulted in an indirect bandgap that may be overcome by thermal excitations, thus corroding the QAHE of the surface state except at very low temperatures. We further provided spectroscopic evidences for homogeneous Cr-doping in the MTIs, indicating that the lack of QAHE was not due to spatially inhomogeneous magnetic order. This work is jointly supported by ARO/MURI (Award #W911NF-16-1-0472) and NSF/IQIM at Caltech (Award #1733907). |
Thursday, March 17, 2022 12:42PM - 12:54PM |
T68.00007: Growth and characterization of GdPS Gokul Acharya, Krishna Pandey, Rabindra Basnet, Md Rafique Un Nabi, Jian Wang, Jin Hu ZrSiS-family materials are well-known topological quantum materials with many exotic properties such as coexistence of nodal-line and non-symmorphic Dirac states, unusual surface state, correlation enhancement, etc. The introduction of magnetism to isostructural LnSbTe (Ln = magnetic lanthanides) has been shown to lead to exotic new quantum states. Here, we report the single crystal growth and characterization of GdPS, a new derivative of ZrSiS-type compounds. The exotic magnetic and transport phenomenon of GdPS offer a new platform to explore quantum phenomenon and topological states. |
Thursday, March 17, 2022 12:54PM - 1:06PM |
T68.00008: Einstein-de Haas effect of topological magnons Trinanjan Datta, Jun Li, Dao-Xin Yao We predict the existence of the Einstein-de Haas effect in topological magnon insulators. Temperature variation of angular momentum in the topological state shows a sign change behavior, akin to the low temperature thermal Hall conductance response. This manifests itself as a macroscopic mechanical rotation of the material hosting topological magnons. We show that an experimentally observable Einstein-de Haas effect can be measured in the square-octagon, the kagome, and the honeycomb lattices. Albeit, the effect is the strongest in the square-octagon lattice. We treat both the low and the high temperature phases using spin wave and Schwinger boson theory, respectively. We propose an experimental set up to detect our theoretical predictions. We suggest candidate square-octagon materials where our theory can be tested. |
Thursday, March 17, 2022 1:06PM - 1:18PM |
T68.00009: Robustness of the nodal line of Fe3GeTe2 to uniaxial strain Byeonghyeon Choi, Mijin Lim, Je-Geun Park, Hyun-Woo Lee We investigate the effect of uniaxial strain on the topological properties of Fe3GeTe2 (FGT). Using first-principles calculations, the anomalous Hall conductivity (AHC) and the band structure are obtained for FGT subjected to strains of various magnitudes and directions. We find surprisingly that the AHC is insensitive to the strain. Recalling that in unstrained FGT, the AHC is dominated by the topological nodal line, we examine the fate of the nodal line under the strain and find that the nodal line degeneracy is robust against the strain even when the strain breaks many geometrical symmetries upon which the existence of the nodal line is based according to previous theories. We finally demonstrate using symmetry analysis that the nodal line of FGT can be maintained robustly with respect to the strain. |
Thursday, March 17, 2022 1:18PM - 1:30PM |
T68.00010: Anisotropic Nodal-Line-Derived Large Anomalous Hall Conductivity in ZrMnP and HfMnP Sukriti Singh, Jonathan Noky, Shaileyee Bhattacharya, Praveen Vir, Yan Sun, Nitesh Kumar, Claudia Felser, Chandra Shekhar The nontrivial band structure of semimetals has attracted substantial research attention in condensed matter physics and materials science in recent years owing to its intriguing physical properties. Within this class, a group of nontrivial materials known as nodal-line semimetals is particularly important. Nodal-line semimetals exhibit the potential effects of electronic correlation in nonmagnetic materials, whereas they enhance the contribution of the Berry curvature in magnetic materials, resulting in high anomalous Hall conductivity (AHC). In this study, two ferromagnetic compounds, namely ZrMnP and HfMnP, are selected, wherein the abundance of mirror planes in the crystal structure ensures gapped nodal lines at the Fermi energy. These nodal lines result in one of the largest AHC values of 2840 Ω−1 cm−1, with a high anomalous Hall angle of 13.6% in these compounds. First-principles calculations provide a clear and detailed understanding of nodal line-enhanced AHC. The finding suggests a guideline for searching large AHC compounds. |
Thursday, March 17, 2022 1:30PM - 1:42PM |
T68.00011: Emergence of spin-current edge states in proximitized graphene in a perpendicular magnetic field Yaroslav Zhumagulov Graphene influenced by the valley-Zeeman intrinsic spin-orbit coupling through proximity effects provides signatures of pseudohelical edge states [1]. Analyzing the band structure of a zigzag graphene nanoribbon in the presence of proximity induced spin-orbit interaction and an external magnetic field, we have discovered the effect of stabilization of intervalley edge states and removal intravalley edge states by the external magnetic field. Stabilization/removal of states is associated with the closing/reopening of the bulk bandgap between nonzero Landau levels [2]. The magnitude of the external magnetic stabilization/removal field was estimated both numerically and analytically. Finally, we have found that stabilized intervalley edge states in the presence or in the absence of a spin-flip hopping through the armchair edge form pseudohelical states or pure spin current states, respectively. The states of pure spin current are formed in wide graphene flakes and are protected from scattering by defects on the zigzag edges of graphene flakes. |
Thursday, March 17, 2022 1:42PM - 2:18PM |
T68.00012: Giant Self-Production of Spin Current and Self-Torque on Single GdFeCo Magnetic Layers Invited Speaker: Juan-Carlos Rojas-Sanchez Two-dimensional spin-textured materials or interfaces are expected to exhibit high efficiency for the interconversion of spin current into charge current1. Magnetic materials possessing strong spin-orbit coupling such as GdFeCo can also efficiently generate spin currents of different symmetries, spin anomalous Hall effect SAHE-like, and spin Hall effect SHE-like. And one such symmetry, SHE-like, could produce what we have coined "self-torque"2,3. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700