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arXiv · 2510.10589

RKKY interaction in Weyl semimetal nanowires

Rohit Mukherjee·Asutosh Dubey
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Abstract

We investigate the effective couplings induced between localized impurities on the surface of a Weyl semimetal (WSM) nanowire within the framework of Ruderman--Kittel--Kasuya--Yosida (RKKY) theory. The itinerant electrons from the chiral Fermi arc surface states mediate impurity-impurity interaction at low energies. As a result, the spin-momentum locking naturally plays a central role in shaping the spin-spin correlations. We show that the dominant interaction channels have distinct origins: while the azimuthal coupling, $J_{\phi\phi}$ term arises exclusively from Fermi arc states with identical spin polarization, the couplings $J_{\mu\nu}$ ($\mu,\nu = z,r$) are governed by Fermi arc states with opposite spin polarizations. Furthermore, we demonstrate that purely surface-mediated contributions exhibit different scaling behavior compared to those involving Fermi arcs and low-energy bulk states. We systematically untangle the contributions from bulk and surface states to the RKKY couplings, using analytical and numerical methods. Our results establish WSM nanowires as a versatile platform for engineering and simulating a broad class of spin models.

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Rohit Mukherjee, Asutosh Dubey. 2025-10-12. RKKY interaction in Weyl semimetal nanowires. https://arxiv.org/abs/2510.10589

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