Optical evidence of the chiral magnetic anomaly in the Weyl semimetal TaAs

A L Levy; A B Sushkov; Fengguang Liu; Bing Shen; Ni Ni; H D Drew; G S Jenkins

doi:10.1103/physrevb.101.125102

Optical evidence of the chiral magnetic anomaly in the Weyl semimetal TaAs

Phys Rev B. 2020;101(12):10.1103/physrevb.101.125102. doi: 10.1103/physrevb.101.125102.

Authors

A L Levy^{1

2}, A B Sushkov¹, Fengguang Liu^{1

3}, Bing Shen⁴, Ni Ni⁴, H D Drew¹, G S Jenkins⁵

Affiliations

¹ Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
² National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, USA.
³ Department of Materials Science and Engineering, Anhui Agricultural University, Hefei 230036, China.
⁴ Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, California 90095, USA.
⁵ Laboratory for the Physical Sciences, College Park, Maryland 20740, USA.

Abstract

Chiral pumping from optical electric fields oscillating at terahertz frequencies is observed in the Weyl material TaAs with electric and magnetic fields aligned along both the $a$ and $c$ axes. Free-carrier spectral weight enhancement is measured directly, confirming theoretical expectations of chiral pumping. A departure from linear field dependence of the Drude weight is observed at the highest fields in the quantum limit, providing evidence of field-dependent Fermi velocity of the chiral Landau level. Implications for the chiral magnetic effect in Weyl semimetals from the optical $f$ -sum rule are discussed.

Grants and funding

9999-NIST/ImNIST/Intramural NIST DOC/United States