Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session D29: Novel Spin and Charge Excitations and their Manipulations in Antiferromagnetic Weyl SemimetalsInvited Session Live Streamed
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Sponsoring Units: GMAG DCMP Chair: Kai Liu, Georgetown University Room: McCormick Place W-190B |
Monday, March 14, 2022 3:00PM - 3:36PM |
D29.00001: Helical magnetism in Weyl materials Invited Speaker: Collin L Broholm The magnetic structures and excitations of topological magnetic semi-metals are of great fundamental interest and key to understanding the unique transport properties of these materials. I will provide an overview of recent neutron and synchrotron x-ray scattering experiments exploring the magnetism of Weyl materials based on transition metals and rare earth elements. I will contrast the commensurate and incommensurate magnetic structures of Mn3Ge and MnSn and relate them to the magnetic excitations and interactions [1,2]. For the rare earth case, I will describe the intricate helical magnetism of NdAlSi and its connection with the underlying electronic band structure [3]. The talk will illustrate the power of novel scattering instrumentation and the importance of combining information from multiple experimental techniques and with theory for a comprehensive understanding of the interplay between charge and spin in topological semi-metals. |
Monday, March 14, 2022 3:36PM - 4:12PM |
D29.00002: Interplay of magnetic order and Weyl nodal structure in NdAlSi Invited Speaker: David Vanderbilt Weyl semimetals are topologically non-trivial phases of matter that sustain low-energy excitations in the massless Weyl fermions. It is necessary to break either inversion or time-reversal symmetry to establish a Weyl semimetal. A rare occasion arises, however, if a material breaks both symmetries. After an introduction to the physics of Weyl semimetals, I will focus on NdAlSi as a paradigmatic example of a noncentrosymmetric magnetic Weyl semimetal. This remarkable system has nodal touchings even if magnetism and spin-orbit coupling are absent, but their populations and locations are strongly affected as these are restored. Using first-principles density functional calculations, we determined the evolution of these Weyl points and their associated electron and hole pockets in both magnetic and nonmagnetic phases, with and without spin-orbit coupling. The possible role of the Weyl structure and associated nesting wavevectors in mediating RKKY interactions and determining the observed form of the magnetic order will also be discussed. |
Monday, March 14, 2022 4:12PM - 4:48PM |
D29.00003: Electrical manipulation and ultrafast dynamics of cluster magnetic octupole in the chiral antiferromagnet Mn3Sn Invited Speaker: Shinji Miwa A magnetic Weyl semimetal is a recent focus of extensive research as it may exhibit large and robust transport phenomena associated with topologically protected Weyl points in momentum space. Mn3Sn is an example of an antiferromagnetic Weyl semimetal that exhibits a large response comparable to the one observed in ferromagnets despite a vanishingly small magnetization [1]. The noncollinear spin order in Mn3Sn can be viewed as a ferroic order of cluster magnetic octupole and breaks the time-reversal symmetry, stabilizing Weyl points and the significantly enhanced Berry curvature near the Fermi energy. Thus, manipulation and understanding of the octupole dynamics form the basis for future control of the antiferromagnetic Weyl semimetal. |
Monday, March 14, 2022 4:48PM - 5:24PM |
D29.00004: Chiral-spin rotation in non-collinear antiferromagneticMn3Sn deiven by spin-orbit torque Invited Speaker: Shunsuke Fukami Electrical control of magnetic materials has been of paramount interest in spintronics research, and many interesting phenomena have been revealed, leading to various opportunities of applications. Non-collinear antiferromagnet with chiral-spin structure is an attractive system showing intriguing properties that were believed to be inherent to ferromagnets such as the anomalous Hall effect [1]. |
Monday, March 14, 2022 5:24PM - 6:00PM |
D29.00005: Giant field-like torque by the out-of-plane magnetic spin Hall effect in a topological antiferromagnet Mn3Sn Invited Speaker: Kouta Kondou Spin-orbit torques (SOT) enable efficient electrical control of the magnetic state of ferromagnets and antiferromagnets. However, the conventional SOT via spin Hall effect (SHE) and Edelstein effect has severe limitation that only in-plane spins accumulate near the surface. Such a SOT is not suitable for controlling perpendicular magnetization, which would be more beneficial for realizing low-power-consumption memory devices. |
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