Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session M59: Antiferromagnetic Kagome metalsFocus
|
Hide Abstracts |
Sponsoring Units: DMP Room: Mile High Ballroom 3C |
Wednesday, March 4, 2020 11:15AM - 11:27AM |
M59.00001: Tuning magnetic properties of a Weyl semimetal with low current density Qiuyuan Wang, Yi Zeng, Kai Yuan, XIng Cheng, Yu Ye Recently, Co3Sn2S2 was proved to be a magnetic Weyl semimetal, which may serve as an ideal platform to realize chiral magnetic effects and quantum anomalous Hall effect. In a perfect quantum anomalous Hall state, theoretical works have predicted that Co3Sn2S2 has a larger domain-wall moving velocity and a smaller field threshold to drive domain-wall motion than conventional metals. This feature is highly attractive for energy-efficient and high-performance spintronic devices, such as magnetic domain-wall racetrack memories. Here we report experimental results of current modulation of the magnetic properties of Co3Sn2S2, and observed a lower current density threshold than conventional metals. |
Wednesday, March 4, 2020 11:27AM - 12:03PM |
M59.00002: Multipole control of large electric and magnetic responses in Weyl antiferromagnets Invited Speaker: Satoru Nakatsuji Antiferromagnets have attracted recent interest for designing next generation high-density and ultrafast spintronics devices because they produce no stray fields and have much faster dynamics. Here we present novel functionality found in chiral antiferromagnets with vanishingly small magnetization, namely, topological Weyl magnets that can be easily controlled by magnetic field, produce large responses, and thus could be useful for applications. In particular, we discuss frustrated antiferromagnets, Mn3X (X =Sn and Ge) as the examples of a magnetic Weyl semimetal or Weyl magnet [1,2,3]. We show that the cluster multipole order on the kagome lattice of Mn moments can be easily controlled and allows the system to exhibit a variety of new functions at room temperature that have never been seen in antiferromagnetic metals. These include the large anomalous Hall and Nernst effects [1,2,4], large magnetic optical Kerr effect [5] and a novel type of spin Hall effect (magnetic spin Hall effect) [6]. Finally, we show that they should be significantly useful for designing antiferromagnetic spintronics [7], and energy harvesting technology for magnets [8]. This presentation is based on the collaboration with T Tomita, T Higo, M Ikhlas, Y Otani, M Kimata, K Kondo, K Kuroda, T Kondo, S Shin, P Goswami, H Chen, A MacDonald, R Arita, M Suzuki, T Koretsune. |
Wednesday, March 4, 2020 12:03PM - 12:15PM |
M59.00003: Magnetic structure of Weyl semi-metal candidate Mn3Sn Youzhe Chen, Jonathan Gaudet, Guy G Marcus, Sayak Dasgupta, Muhammad Ikhlas, Taishi Chen, Takahiro Tomita, Jiao Lin, Wangchun Chen, Yang Zhao, Matthew Stone, Satoru Nakatsuji, Oleg Tchernyshyov, Collin Leslie Broholm The interplay between frustrated magnetism and itinerant electrons can give rise to topogical non-trivial properties such as anomalous Hall and Nernest effects in Mn3Sn. Denisty functional thoery shows Weyl points close to Fermi energy are responsible for anomalous transport properties and can be controled by magnetism via spin-orbit coupling. |
Wednesday, March 4, 2020 12:15PM - 12:27PM |
M59.00004: Magnetic Phase Diagram of Non-Collinear Antiferromagnetic Weyl Metal Mn3+xSn1-x Muhammad Ikhlas, Takahiro Tomita, Satoru Nakatsuji The non-collinear antiferromagnet Mn3Sn shows large spontaneous time-reversal odd responses [1-4] in the inverse triangular spin structure state, which are considered to be signatures of Weyl nodes near the Fermi energy [5]. Mn3Sn single crystals are known to be stable in the presence of excess manganese atoms. Depending on the composition, three distinct magnetic phases can be realized as a function of temperature, namely the high temperature triangular spin structure phase (q =0), the intermediate-temperature helical phase (q ≠ 0), and the low-temperature cluster spin glass phase [7]. Here we present our study on the compositional dependence of Mn3-xSn1-x and discuss the systematic evolution of the three magnetic phases in Mn3Sn based on transport and magnetic properties. |
Wednesday, March 4, 2020 12:27PM - 12:39PM |
M59.00005: Observation of zero bias anomaly in noncolinear antiferromagnet/heavy metal heterostructures JOYNARAYAN MUKHERJEE, Karthik Raman Noncolinear antiferromagnets (NC-AFMs) show exotic transport phenomena such as anomalous and topological Hall effect due to their non-vanishing Berry curvature1. Although many reports have focused on the transport properties of NC-AFMs, we have explored the differential conductance spectroscopy to probe the electronic structure of heterostructured device comprising of NC-AFM, Mn3Pt, in proximity to heavy metal(Ta). Mn3Pt/Ta and Ta/Mn3Pt/Ta heterostructures were grown by co-sputtering on STO (100) substrate. We observe a strong zero bias conductance peak (ZBCP), only in the Mn3Pt/Ta structure, below 10 K with the peak amplitude increasing with cool down and saturating at 4 K, with a magnitude of 4 times the conductance in the flat regime at high bias. Additionally, we observe sister peaks on both sides of the ZBCP twice in magnitude of conductance in the flat regime. Similar phenomena are reported in Dirac semimetal/superconductor heterostructure2 attributed to the superconducting nature of the device. Our study therefore, highlights that such ZBCP may be observed even in non-superconducting devices and may be driven by interface effects in these topologically nontrivial materials. |
Wednesday, March 4, 2020 12:39PM - 12:51PM |
M59.00006: A new stress dilatometer, and measurement of the thermal expansion under uniaxial stress of Mn3Sn Kent Shirer, Muhammad Ikhlas, Po-Ya Yang, Andrew Mackenzie, Clifford W. Hicks, Satoru Nakatsuji We present new a new device for measuring the thermal expansion of materials under tunable uniaxial stress. We have performed first measurements on Mn3Sn - a room temperature antiferromagnet (AFM) that exhibits a spontaneous Hall effect [1]. Measurement of thermal expansion provides thermodynamic data about the nature of phase transitions, and uniaxial stress provides a powerful tuning method that does not introduce disorder. Mn3Sn exhibits an anomaly in its thermal expansion near ~270 K, associated with a first order change in the magnetic structure. We show that this transition temperature is suppressed under uniaxial compression along the c-axis. These results show the efficacy of our stress-dilatometer as well as provide new, thermodynamic insight into the response to applied stress of Mn3Sn. |
Wednesday, March 4, 2020 12:51PM - 1:03PM |
M59.00007: Magnetic and topological properties of Kagome metal YMn6Sn6 Nirmal Ghimire, Lekhanath Poudel, Rebecca Dally, Nishchal Thapa Magar, Nicholas Bishop, Michael McGuire, J Samuel Jiang, Igor Mazin, John Mitchell, Jeffrey Lynn The Kagome lattice has historically been known for frustration-driven novel phenomena, such as spin-liquid phases. Recent experiments have indicated that 3D kagome magnets provide a natural platform to study the effect of the interplay between magnetism and electronic topology. For example, Weyl fermions and a non-collinear spin texture are observed in Mn3Sn, heavy Dirac bands are reported in frustrated ferromagnet Fe3Sn2, and flat bands and Dirac cones are realized in antiferromagnetic FeSn. Here we present our recent findings of the complex nature of the magnetism and topological features in the electronic structure of a ternary kagome magnet, YMn6Sn6. This compound orders with a commensurate antiferromagnetic helical structure below 340 K, which on cooling shows an incommensurate double helical structure. Both wave vectors are temperature dependent with the difference in q between the two helices gradually decreasing with decreasing temperature but remaining in the ground state. Electronic band structure calculations show the presence of a Dirac point near the Fermi energy, and a linear magnetoresistance is observed at low temperature when a magnetic field is applied along c-axis. |
Wednesday, March 4, 2020 1:03PM - 1:15PM |
M59.00008: Neutron diffraction results on the in-field magnetic structure of YMn6Sn6 Rebecca Dally, Lekhanath Poudel, Nishchal Thapa Magar, Markus Bleuel, J Samuel Jiang, Michael McGuire, John Mitchell, Jeffrey Lynn, Nirmal Ghimire A current focus of condensed matter physics is to find materials where magnetism can tune topological properties or vice versa. Research has focused on the study of non-centrosymmetric compounds with Dzyaloshinskii-Moriya interactions, but recent studies suggest that magnetic frustration is another route to search for topological properties. Our measurements indicate that YMn6Sn6 is a promising candidate to explore the interplay of magnetic and topological properties. It is a centrosymmetric, antiferromagnetic (AF) metal with layered kagome networks of magnetic Mn atoms. The ground state magnetic structure is helical and competing ferromagnetic and AF interlayer exchange is the source of frustration in the system. The structure is far from standard though, as two, long-range, incommensurate wavevectors persist throughout a large region of the B-T phase space. We will focus on neutron diffraction data that track the evolution of these two wavevectors as a function of magnetic field, which clearly elucidates the nature of the multiple field-induced transitions seen in AC susceptibility. Additionally, the topological Hall resistivity undergoes changes as a function of field that can be connected to those in the magnetic structure, signifying a strong interplay between the two. |
Wednesday, March 4, 2020 1:15PM - 1:27PM |
M59.00009: Transport evidence of Chern gapped Dirac fermions in the kagome magnet TbMn6Sn6 Xitong Xu, Wenlong Ma, Huibin Zhou, Shuang Jia The kagome magnet TbMn6Sn6 is a new member of correlated topological metals, featuring Chern gapped Dirac fermions from the spinless Haldane model. Here we report combined electric and thermal transport study of TbMn6Sn6. Quantum oscillations are observed both in magnetoresistance and magneto-thermopower. The derived Fermi length, the cyclotron mass and their angle-dependence confirm the picture of 2D Dirac dispersion in this hard magnet. Besides, we observe complex Fermi surfaces arising from interlayer interactions, which probably consist of 2D networks and 3D sheets. We also found a phase reversal in the thermal conductivity oscillations, which may be related to competition between electronic contribution and electron-phonon interaction in thermal conductivity. Our observations provide crucial information for theoretical modelling this quantum material. |
Wednesday, March 4, 2020 1:27PM - 1:39PM |
M59.00010: Molecular epitaxy growth of antiferromagnetic Kagome metal FeSn Hisashi Inoue, Minyong Han, Linda Ye, Takehito Suzuki, Joseph G Checkelsky Kagome metals are metals with the crystal structures of the kagome lattice, the two-dimensional structure with atoms arranged in corner-sharing triangles, and other two-dimensional layers. The hexagonal arrangement and the lattice symmetry produce Dirac fermions in its band structure [1]. FeSn is an antiferromagnetic version of kagome metal where magnetic element Fe populates the kagome lattice. Taking advantage of magnetic interactions, FeSn is a promising platform to control the properties of Dirac fermions by the magnetic degree of freedom in electronic devices. Here we report the first realization of high quality epitaxial FeSn thin films [2]. Using optimized growth schemes, and electrical and magnetic torque measurements, we observed that the thin films show residual resistivity ratio between 300 K and 2 K up to 24, and support an antiferromagnetic ordering temperature 353 K comparable to the bulk one. This opens a route toward electronic and spintronics device applications of magnetic Dirac fermions. |
Wednesday, March 4, 2020 1:39PM - 1:51PM |
M59.00011: Magnetic Imaging of Antiferromagnetic Domain Walls in Magnetic Topological Materials Paul Sass, Wenbo Ge, Weida Wu, Jiaqiang Yan, Dimuthu Obeysekera, Junjie Yang The study and control of domains and domain walls (DW) in topological materials is crucial to understanding and utilizing their exotic phenomena, such as axion insulator and quantum anomalous Hall states1-3. Domains of alternating sign in these materials cancel out these states and thus it is imperative to understand how these antiferromagnetic (AFM) domains form and can be controlled. Despite many efforts, it has been challenging to directly visualize AFM domains or DWs with nanoscale resolution in general, especially in magnetic field. Here, we report the magnetic imaging of domains and DWs in several uniaxial AFMs, the topological insulator MnBi2Te4 family4 and the topological semimetal EuMnBi25, using cryogenic magnetic force microscopy (MFM)6. Our MFM results reveal higher magnetic susceptibility or net moments inside the DWs than in domains. DWs in these AFMs form randomly with strong thermal and magnetic field dependences. |
Wednesday, March 4, 2020 1:51PM - 2:03PM |
M59.00012: Topological surfaces states of MnBi2Te4 at finite temperatures and at domain walls Kevin Garrity, Sugata Chowdhury, Francesca Tavazza MnBi2Te4 has recently been the subject of intensive study, due |
Wednesday, March 4, 2020 2:03PM - 2:15PM |
M59.00013: Mobius Insulator and Higher-Order Topology in MnBi2nTe3n+1 Ruixing Zhang, Fengcheng Wu We propose MnBi2nTe3n+1 as a magnetically tunable platform for realizing various symmetry-protected higher-order topology. Its canted antiferromagnetic phase can host exotic topological surface states with a Mobius twist that are protected by nonsymmorphic symmetry. Moreover, opposite surfaces hosting Mobius fermions are connected by one-dimensional chiral hinge modes, which offers the first material candidate of a higher-order topological Mobius insulator. We uncover a general mechanism to feasibly induce this exotic physics by applying a small in-plane magnetic field to the antiferromagnetic topological insulating phase of MnBi2nTe3n+1, as well as other proposed axion insulators. For other magnetic configurations, two classes of inversion-protected higher-order topological phases are ubiquitous in this system, which both manifest gapped surfaces and gapless chiral hinge modes. We systematically discuss their classification, microscopic mechanisms, and experimental signatures. Remarkably, the magnetic-field-induced transition between distinct chiral hinge mode configurations provides an effective ``topological magnetic switch". |
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