• Open Access

Current at a Distance and Resonant Transparency in Weyl Semimetals

Yuval Baum, Erez Berg, S. A. Parameswaran, and Ady Stern
Phys. Rev. X 5, 041046 – Published 21 December 2015

Abstract

Surface Fermi arcs are the most prominent manifestation of the topological nature of Weyl semimetals. In the presence of a static magnetic field oriented perpendicular to the sample surface, their existence leads to unique intersurface cyclotron orbits. We propose two experiments that directly probe the Fermi arcs: a magnetic-field-dependent nonlocal dc voltage and sharp resonances in the transmission of electromagnetic waves at frequencies controlled by the field. We show that these experiments do not rely on quantum mechanical phase coherence, which renders them far more robust and experimentally accessible than quantum effects. We also comment on the applicability of these ideas to Dirac semimetals.

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  • Received 27 August 2015

DOI:https://doi.org/10.1103/PhysRevX.5.041046

This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Authors & Affiliations

Yuval Baum1, Erez Berg1, S. A. Parameswaran2, and Ady Stern1

  • 1Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
  • 2Department of Physics and Astronomy, University of California, Irvine, California 92697, USA

Popular Summary

Weyl semimetals are a new class of conducting materials characterized by a nontrivial, topological band structure. Research has suggested that Weyl semimetals can exhibit unusual physical phenomena, such as the Adler-Bell-Jackiw chiral anomaly and a special type of quantum oscillations associated with Fermi arc surface states. Here, we expand on these ideas, and we show that, already at the semiclassical level, Fermi arcs leave a striking imprint on both the ac and dc response properties of Weyl semimetals. In particular, we demonstrate via two experiments that the generation of an electrical current is possible given the buildup of voltage at a spatially removed location.

We demonstrate that, in the presence of a static applied magnetic field, the cyclotron orbits on Fermi arcs, which can modulate the resistance of a material, lead to the generation of a nonlocal current across the extent of a sample. Furthermore, this situation causes the sample to be resonantly transparent to electromagnetic radiation in the microwave regime (5–500 GHz). We recover this transparency even for thick samples (i.e., cases in which a standard metal would reflect the radiation). Slabs of Weyl semimetals can accordingly act as narrow bandpass filters of microwave radiation, and the resonant transmission frequency can be tuned by an applied magnetic field. We find that these effects are, to a surprising degree, protected against the dominant type of disorder expected in these systems. These phenomena provide a novel and robust way to unambiguously detect Fermi arcs, which are indicative of the topological properties of Weyl semimetals.

Our findings highlight a fundamentally new class of physics effects related to the controlled generation of nonlocal currents in three-dimensional Weyl and Dirac semimetals. Our results demonstrate that semiclassical experiments open the door to studying Weyl semimetals free of the requirements of extremely low temperatures and high-purity samples.

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Vol. 5, Iss. 4 — October - December 2015

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