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arXiv · 2310.04394

Spin-Mediated Direct Photon Scattering by Plasmons in BiTeI

A. C. Lee·S. Sarkar·K. Du·H. -H. Kung·C. J. Won·K. Wang·S. -W. Cheong·S. Maiti·G. Blumberg
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Abstract

We use polarization resolved Raman spectroscopy to demonstrate that for a 3D giant Rashba system the bulk plasmon collective mode can directly couple to the Raman response even in the long wavelength $\mathbf q \rightarrow 0$ limit. Although conventional theory predicts the plasmon spectral weight to be suppressed as the square of its quasi-momentum and thus negligibly weak in the Raman spectra, we observe a sharp in-gap plasmon mode in the Raman spectrum of BiTeI below the Rashba continuum. This coupling, in a polar system with spin-orbit coupling, occurs without assistance from phonons when the incoming photon excitation is resonant with Rashba-split intermediate states. We discuss the distinctive features of BiTeI's giant Rashba system band structure that enable the direct observation of plasmon in Raman scattering.

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A. C. Lee, S. Sarkar, K. Du, H. -H. Kung, C. J. Won, K. Wang, S. -W. Cheong, S. Maiti, G. Blumberg. 2023-10-06. Spin-Mediated Direct Photon Scattering by Plasmons in BiTeI. https://doi.org/10.1103/physrevb.109.l041111

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