Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session W68: Electronic Structure of Magnetic Topological MaterialsFocus Recordings Available
|
Hide Abstracts |
Sponsoring Units: DMP GMAG DCMP Chair: Zijia Cheng, Princeton University; Liqin Ke, Ames Lab Room: Hyatt Regency Hotel -Hyde Park B |
Thursday, March 17, 2022 3:00PM - 3:12PM |
W68.00001: Electronic structure analysis of EuX2As2 (X=Cd, Zn): elucidating the interplay of crystallographic structure, magnetism, and topology Emily M Been, Zhi-Cheng Wang, Jonathan Gaudet, Kyle Fruhling, Xiaohan Yao, Uwe H Stuhr, Yi Cui, Chunjing Jia, Brian Moritz, Thomas P Devereaux, Fazel Tafti A particular family of materials containing Eu are an interesting set of compounds for studying the interplay between structure, magnetism, and topology. To elucidate the factors that control their resistive anisotropy, we are studying EuCd2As2 compared to its analogue EuZn2As2. Replacing Cd with Zn reduces the spin-orbit coupling, the $d$-electrons are more localized, and the Nèel-temperature increases by a factor of two, but DFT calculations show strikingly small total energy differences (∼5 meV) between different magnetic configurations for both EuCd2As2 and EuZn2As2. The implication for experiments is that the magnetic ground-state of EuX2As2 can be manipulated easily by external pressure, strain, or disorder, making EuX2As2 an exciting platform for tuning a topological bandstructure through the magnetic order. |
Thursday, March 17, 2022 3:12PM - 3:24PM |
W68.00002: Electronic structure and topology across Tc in the magnetic Weyl semimetal Co3Sn2S2 Antonio Rossi, Vsevolod M Ivanov, Sudheer Anand Sreedhar, Adam Gross, Zihao Shen, Eli Rotenberg, Aaron Bostwick, Christopher Jozwiak, Valentin Taufour, Sergey Y Savrasov, Inna Vishik Half-metallic ferromagnet Co3Sn2S2 was recently predicted and experimentally confirmed to host topological Weyl points just above the Fermi energy. Using a combination of tight binding models and first principles calculations, we present an analysis of the electronic structure and magnetism in this material. We argue that Co3Sn2S2 evolves from a Mott ferromagnet below the Curie temperature (Tc = 177K) to a correlated metallic state above Tc. We show how the magnetism in Co3Sn2S2 can be represented using a tight-binding model consisting of Co-3dx2-y2 orbitals on the kagome lattice. At an electron filling of 5/6, this model reproduces the experimentally observed magnetism and results in a reduction of the Coulomb interaction due to cluster effects. This reduced value of Hubbard U leads to the Hubbard bands collapsing into a single quasiparticle band across the magnetic transition, creating a correlated metallic state. The consequences of this complex magnetic transition for the topology in this material are discussed with the aid of first principles calculations of the correlated system. |
Thursday, March 17, 2022 3:24PM - 3:36PM |
W68.00003: Band structure reconstruction in rare-earth monopnictides in the magnetically ordered state. Yevhen Kushnirenko, Benjamin Schrunk, Brinda Kuthanazhi, Kyungchan Lee, Junyeong Ahn, Lin-Lin Wang, Evan O'Leary, Robert-Jan Slager, Andrew Eaton, Sergey L Budko, Paul C Canfield, Adam Kaminski Many members of rare-earth monopnictides exhibit antiferromagnetic transition at low temperatures, with some having more than one magnetically ordered state. Recently, the existence of several types of topologically non-trivial states, including Wely semimetal, were predicted to occur in several of these compounds with signatures of topological states observed in transport measurements and STS measurements. Our ARPES data revealed complex reconstruction of band structure upon development of long range order with some features consistent with presence of topological states. |
Thursday, March 17, 2022 3:36PM - 3:48PM |
W68.00004: Electronic structure of a new magnetic Weyl semimetal candidate CeAlSi by using ARPES Anup Pradhan Sakhya, Gyanendra Dhakal, Cheng-Yi Huang, Sabin Regmi, Hsin Lin, Bahadur Singh, Fazel Tafti, Arun Bansil, Madhab Neupane Weyl semimetals with Weyl fermions denotes an electronic phase of matter in which two bands cross linearly in space. Here, using high-resolution angle-resolved photoemission spectroscopy, we have clearly resolved the distinct surface Fermi arcs along the Γ-M direction on the (001) surface of the candidate magnetic Weyl semimetal CeAlSi. In addition to this, the soft X-ray ARPES data shows the presence of Weyl nodes in this material. The obtained ARPES results are further supported by our systematic electronic structure calculations, thus confirming the presence of Fermi arcs and Weyl nodes in this material. |
Thursday, March 17, 2022 3:48PM - 4:00PM |
W68.00005: Observation of flat bands in a near room temperature van der Waals Ferromagnet Han Wu, Paul T Malinowski, Yue Shi, Jian-Xin Zhu, Yu He, Ji Seop Oh, Jianwei Huang, Mason Klemm, Xiaokun Teng, Xiang Chen, Makoto Hashimoto, Donghui Lu, Sung-Kwan Mo, Pengcheng Dai, Robert J Birgeneau, Jiun-Haw Chu, Ming Yi The two-dimensional (2D) van der Waals magnets has attracted much attention recently due to their tunability and versatility towards a new generation of spintronic devices. Here we present evidence from high resolution angle-resolved photoemission spectroscopy study of a near room-temperature ferromagnet Fe5-xGeTe2. Interestingly, we resolve a number of electronic dispersions that remain flat across a large portion of the Brillouin zone. In addition, we will present evidence for Dirac crossings that reveal the non-trivial topological properties of this material. The temperature evolution of the electronic structure across Tc will also be discussed. Overall, our observations reveal Fe5-xGeTe2 to be a rich material platform for understanding correlation and magnetism in the presence of non-trivial topology. |
Thursday, March 17, 2022 4:00PM - 4:12PM |
W68.00006: Signatures of magnetic Weyl fermion annihilation Tyler A Cochran, Ilya Belopolski, Xiaoxiong Liu, Zijia Cheng, Xian Yang, Praveen Vir, Gohil S Takur, Claudia Felser, Titus Neupert, Zahid M Hasan The manipulation of topological states in quantum matter is an essential pursuit of fundamental physics and next-generation quantum technology. Here we report the magnetic manipulation of Weyl fermions in the kagome spin-orbit semimetal Co3Sn2S2, observed by high-resolution photoemission spectroscopy. We demonstrate the exchange collapse of spin-orbit-gapped ferromagnetic Weyl loops into paramagnetic Dirac loops under suppression of the magnetic order. We further observe that topological Fermi arcs disappear in the paramagnetic phase, suggesting the annihilation of exchange-split Weyl points. Our findings indicate that magnetic exchange collapse naturally drives Weyl fermion annihilation, opening new opportunities for engineering topology under correlated order parameters. |
Thursday, March 17, 2022 4:12PM - 4:24PM |
W68.00007: Ultra-high magnetoresistance and field-induced Fermi surface reconstruction in a topological magnet Kevin J Allen, Shiming Lei, Jaime M Moya, Emilia Morosan Square lattice compounds have attracted much attention in the field of topological materials and complex magnetism. Recently it has been established that many different types of square-net materials, beyond nonsymmorphic space groups, can host Dirac fermions coming from band folding and electron count. In this talk I will discuss our recent results on a layered square lattice compound where ultra-high magnetoresistance (> 200,000%, T = 2 K, H = 14 T) is observed when magnetic order sets in. Through ARPES measurement and DFT calculation we identify a symmetry protected Dirac cone near the Fermi level, which we expect to be responsible for the observed high magnetoresistance and high carrier mobility. We also studied the field induced Fermi surface reconstruction across the magnetic transition. The interplay of magnetism and band topology point to rich physics in this material system. |
Thursday, March 17, 2022 4:24PM - 4:36PM |
W68.00008: Composite Weyl loops in magnetic topological semimetals Ilya Belopolski, Tyler A Cochran, Zijia Cheng, Xian Yang, Jia-Xin Yin, Guoqing Chang, Kaustuv Manna, Claudia Felser, Zahid M Hasan The discovery of magnetic Weyl semimetals has propelled the investigation of electronic topology in correlated systems. Many topological correlated and magnetic materials exhibit complex electronic structures at the Fermi level, which are essential in driving anomalous response and exhibit rich interplay with correlated order parameters. However, systematic characterization of the complete topological properties near the Fermi level in complex semimetals remains limited. Here I disentangle the rich topological structure of Co2MnGa through bulk-sensitive soft X-ray angle-resolved photoemission spectroscopy combined with ab initio calculations [1,2]. I experimentally examine the system on multiple cleaving planes and identify three distinct families of Weyl loops, demonstrating a rich composite Weyl loop structure at the Fermi level. I discuss the implications of our findings for exotic transport in Co2MnGa and related magnetic Weyl systems [3,4]. |
Thursday, March 17, 2022 4:36PM - 4:48PM |
W68.00009: The Interplay of Weyl electronic structure with long-range magnetic structure in CoxFe1-x Ge compounds Bushra Sabir The interplay between magnetism and topology plays a revolutionary role in material research, providing an additional means to control the symmetries exhibited by materials and opening the possibility for the next-generation electronic devices. In this work, we study alloys of the B20 Chiral crystals CoxFe1-xGe for x=0.1, 0.2, via density functional theory by investigating the electronic structure and topological properties by symmetry analysis of the multiplicity of the bands and their degeneracy. Our results reveal that magnetization increases smoothly from nonmagnetic CoGe to ferromagnetic CoxFe1-xGe when x=0.1,0.2. The effect of Spin-orbit coupling (SOC) is systematically varied simultaneously with the magnetic structure to investigate the topological Weyl crossing points. Long Fermi arcs are observed connecting their surface projections that confirm the Weyl fermionic behavior consistent with other work. Variation in magnetic structure and SOC determine the shape, size, and seemingly the chirality of Fermi arcs. We also develop a simple tight-binding model to confirm Weyl points (WP) calculations for our system. Thus, our results reveal that CoxFe1-xGe Weyl semimetals are excellent materials to experimentally explore quantum topological phases by tuning unconventional chiral fermions. |
Thursday, March 17, 2022 4:48PM - 5:00PM |
W68.00010: Evolution of Electronic and Magnetic Properties in Topological Semimetal SmSbxTe2-x Krishna Pandey, Rabindra Basnet, Gokul Acharya, Md Rafique Un Nabi, Jian Wang, Jin Hu The ZrSiS-type topological material family has attracted growing interests. The magnetic member of the ZrSiS-family, LnSbTe (Ln = magnetic lanthanides), are ideal candidates to explore novel exotic states due to coupling between magnetism and topology. Here we present experimental investigation on SmSbxTe2-x. The evolution of structural, magnetic, thermodynamic, and electronic properties with varying Sb-Te composition is studied. Our finding reveals that the SmSbxTe2-x material could be a rare platform to investigate novel quantum phenomena as a result of inherent magnetism, topology, and possible enhanced electronic correlations. |
Thursday, March 17, 2022 5:00PM - 5:12PM |
W68.00011: ARPES study of the Mn-Bi-Te natural heterostructural families Bryan Berggren, Rafal Kurleto, Dushyant Narayan, Chaowei Hu, Tiema Qian, Ni Ni, Dan S Dessau Magnetic Topological Insulators (MTI) are a group of quantum materials that combine non-trivial band topology and magnetic order, making them candidates for hosting quantum phenomena such as the quantum anomalous Hall Effect, axion insulator state, and quantum magnetoelectric effect. The first candidate for an intrinsic MTI is MnBi2Te4, a material made up of van der Waals-bonded septuple layers, with Mn atoms providing anti-ferromagnetic order below the Neel temperature of 25 K. For this talk, I present and discuss angle-resolved photoemission spectroscopy (ARPES) measurements on MnBi2Te4 and related natural heterostructure compounds. In MnBi2Te4, the evolution of bulk conduction bands and the topological surface state is observed above and below the Neel temperature. In the ARPES measurements, different photon energies appear to select between bulk and surface bands, assisting the use of two-dimensional fitting procedures to help quantify the effect of magnetic order on the bands at the Dirac point. |
Thursday, March 17, 2022 5:12PM - 5:48PM |
W68.00012: Electronic structures of magnetic topological insulator Invited Speaker: Tay-Rong Chang In the past decade, the correlation between symmetry and topology have taken the central stage of modern physics. It has attracted intensive research interests in condensed matter physics and materials science since the discovery of various topological materials such as quantum spin Hall insulators, 3D topological insulators, and inversion-symmetry breaking Weyl semimetals. Despite tremendous progress, the majority of known topological materials are nonmagnetic while the novel magnetic topological materials have remains elusive. In the last few years, the focus has shifted from nonmagnetic phase to magnetic topological material. In this talk, we will review a range of materials including antiferromagnetic topological insulator [1], magnetic kagome family RMn6Sn6 (R = Tb,Gd) [2], axion insulator [3], and the antisite effects in magnetic topological phase transitions [4] via first-principles calculations, and discuss various exotic phenomena observed experimentally in these new materials. |
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