Probing the edge states of Chern insulators using microwave impedance microscopy
[1];
[2];
[4];
- University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, San Diego, CA (United States)
- University of California, San Diego, CA (United States)
- Massachusetts Institute of Technology (MIT), Cambridge, MA (United States)
- RIKEN Center for Emergent Matter Science (CEMS), Saitama (Japan)
- Stanford University, CA (United States); Stanford Linear Accelerator Center National Accelerator Laboratory, Menlo Park, CA (United States)
Microwave impedance microscopy (MIM) has been utilized to directly visualize topological edge states in many quantum materials. While the microwave response for conventional metals and insulators can be accurately quantified using simple lumped-element circuits, whose applicability to more exotic quantum systems remain limited. In this work, we present a general theoretical framework of the MIM response of arbitrary quantum materials. Applying it to topological edge states in a Chern insulator predicts an enhanced MIM response at the crystal boundaries due to collective edge magnetoplasmon (EMP) excitations. The unique resonance frequency of these plasmonic modes allows one to disentangle the signatures of topological versus trivial edge states. To benchmark our analytical predictions, we experimentally probe the MIM response of quantum anomalous Hall edge states in a Cr-doped (Bi,Sb)2Te3 topological insulator and perform numerical simulations using a classical formulation of the EMP modes based on this realistic tip-sample geometry, both of which yield results consistent with our theoretical picture. Here we also show how the technique of MIM can be used to quantitatively extract the topological invariant of a Chern insulator and shed light on the microscopic nature of dissipation along the crystal boundaries.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- Air Force Office of Scientific Research (AFOSR); Gordon and Betty Moore Foundation; Japan Science and Technology Agency; National Science Foundation (NSF); UC Laboratory Fees Research Program; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE); USDOE Office of Science (SC), High Energy Physics (HEP)
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 2338084
- Journal Information:
- Physical Review. B, Journal Name: Physical Review. B Journal Issue: 23 Vol. 108; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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