Speaker
Description
We study electronic Raman scattering (eRS) from low-energy excitations in many-electron metallic systems lacking inversion symmetry. In these systems, spin–orbit coupling lifts spin degeneracy at the Fermi level, enabling incoherent spin-flip excitations and coherent chiral-spin modes, which can be probed via Raman spectroscopy. These excitations have been experimentally observed using resonant eRS in a variety of systems, including $CdTe$ quantum wells [1,2], topological surface states of $Bi_2Se_3$ [3], and moiré superlattices formed by $WSe_2/WS_2$ heterostructures [4].
Despite these advances, a clear understanding of how inversion symmetry breaking modifies light–matter interactions remains incomplete, particularly in the non-resonant regime relevant for systems such as graphene, where electronic states do not resonantly couple to typical Raman photons. Non-resonant Raman scattering in monolayer and bilayer graphene has been studied theoretically and experimentally [5,6], but inversion symmetry is preserved.
Here, we investigate modifications of the effective light–matter interaction vertex in both single- and multi-valley systems with spin–orbit coupling in the non-resonant limit. Our results show that inversion symmetry breaking produces polarization-dependent Raman signatures, whose characteristics depend on the type of substrate-induced spin–orbit coupling and the Hilbert space considered.
References:
[1] F. Perez et al., Phys. Rev. Lett. 99, 026403 (2007)
[2] S. Maiti & D. L. Maslov, Phys. Rev. B 95, 134425 (2017)
[3] H.-H. Kung et al., Phys. Rev. Lett. 119, 136802 (2017)
[4] Z. Shan et al., arXiv:2509.16511 (2025)
[5] O. Kashuba & V. I. Fal’ko, Phys. Rev. B 80, 241404 (2009)
[6] E. Riccardi et al., Phys. Rev. Mater. 3, 014002 (2019)
| Keyword-1 | Spin-orbit coupling |
|---|---|
| Keyword-2 | Electronic Raman scattering |
| Keyword-3 | Inversion symmetry breaking |