Anomalous Hall Transport by Optically Injected Isospin Degree of Freedom in Dirac Semimetal Thin Film

Chirality of massless fermions emerging in condensed matter is a key to understand their characteristic behavior as well as to exploit their functionality. However, the chiral nature of massless fermions in Dirac semimetals has remained elusive, due to equivalent occupation of carriers with the oppo...

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Bibliographic Details
Published in:Nano letters 2024-01, Vol.24 (1), p.222-228
Main Authors: Murotani, Yuta, Kanda, Natsuki, Fujimoto, Tomohiro, Matsuda, Takuya, Goyal, Manik, Yoshinobu, Jun, Kobayashi, Yohei, Oka, Takashi, Stemmer, Susanne, Matsunaga, Ryusuke
Format: Article
Language:English
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Summary:Chirality of massless fermions emerging in condensed matter is a key to understand their characteristic behavior as well as to exploit their functionality. However, the chiral nature of massless fermions in Dirac semimetals has remained elusive, due to equivalent occupation of carriers with the opposite chirality in thermal equilibrium. Here, we show that the isospin degree of freedom, which labels the chirality of massless carriers from a crystallographic point of view, can be injected by circularly polarized light. Terahertz Faraday rotation spectroscopy successfully detects the anomalous Hall conductivity by a light-induced isospin polarization in a three-dimensional Dirac semimetal, Cd3As2. Spectral analysis of the Hall conductivity reveals a long scattering time and a long decay time, which are characteristic of the isospin. The long-lived, robust, and reversible character of the isospin promises a potential application of Dirac semimetals in future information technology.
ISSN:1530-6984
1530-6992
DOI:10.1021/acs.nanolett.3c03770