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arXiv · 2112.07033

Giant intrinsic anomalous terahertz Faraday rotation in the magnetic Weyl semimetal Co$_2$MnGa at room temperature

Xingyue Han·Anastasios Markou·Jonathan Stensberg·Yan Sun·Claudia Felser·Liang Wu
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Abstract

We report measurement of terahertz anomalous Hall conductivity and Faraday rotation in the magnetic Weyl semimetal Co$_2$MnGa thin films as a function of the magnetic field, temperature and thickness, using time-domain terahertz spectroscopy. The terahertz conductivity shows a thickness-independent anomalous Hall conductivity of around 600 $\Omega^{-1}\cdot cm^{-1}$ at room temperature, and it is also frequency-independent from 0.2-1.5 THz. The magnitude of the longitudinal and Hall conductivities, the weak spin-orbit coupling, and the very close positioning of Weyl points to the chemical potential all satisfy the criteria for intrinsic anomalous Hall conductivity. First-principle calculation also supports the frequency-independent intrinsic anomalous Hall conductivity at low frequency. We also find a thickness-independent Faraday rotation of 59 ($\pm6$) mrad at room temperature, which comes from the intrinsic Berry curvature contribution. In the thinnest 20 nm sample, the Faraday rotation divided by the sample thickness reaches around 3 mrad/nm due to Berry curvature, and is the largest reported at room temperature. The giant Verdet constant of the order of 10 $^{6}$ rad m $^{-1}$ T $^{-1}$ at room temperature and the large Hall angle around 8.5 $\%$ from 0.2-1.5 THz indicates that Co$_2$MnGa is promising for THz spintronics at room temperature.

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Xingyue Han, Anastasios Markou, Jonathan Stensberg, Yan Sun, Claudia Felser, Liang Wu. 2021-12-13. Giant intrinsic anomalous terahertz Faraday rotation in the magnetic Weyl semimetal Co$_2$MnGa at room temperature. https://doi.org/10.1103/physrevb.105.174406

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