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arXiv · 2603.09362

Interplay of Rashba spin-orbit coupling and Coulomb interaction in topological spin-triplet excitonic condensates

Quoc-Huy Ninh·Huu-Nha Nguyen·Van-Nham Phan
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Abstract

The cooperative effect of Rashba spin-orbit coupling (SOC) and Coulomb attraction in stabilizing topological spin-triplet excitonic condensates (ECs) in two-dimensional electron-hole systems in external magnetic field is investigated by using an unrestricted Hartree-Fock approach combined with the random-phase approximation. At weak electron-hole Coulomb interaction, the intraband Rashba SOC induces spin-momentum locking and topological semimetal behavior, while stronger interaction stabilizes spin-triplet ECs. Increasing the valence-band SOC drives a transition from a topologically trivial EC with coexisting spin-up and spin-down components to a topological spin-up EC only with quantized Chern number $C=2$. The dynamical excitonic susceptibility reveals a soft spin-up triplet mode acting as the precursor of the condensate. These results establish a microscopic mechanism for Rashba SOC-induced topological ECs and suggest realistic situations for their realization in noncentrosymmetric Janus transition-metal dichalcogenides and twisted van der Waals heterostructures.

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Quoc-Huy Ninh, Huu-Nha Nguyen, Van-Nham Phan. 2026-03-10. Interplay of Rashba spin-orbit coupling and Coulomb interaction in topological spin-triplet excitonic condensates. https://doi.org/10.1103/bybf-jcmt

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