Indirect magnetic signals mediated by a single surface band in Weyl semimetals

TL;DR

This paper investigates how a single surface band in Weyl semimetals mediates magnetic interactions, revealing unique oscillation patterns that could serve as signals for surface state detection despite impurity scattering.

Contribution

It introduces a model showing that a single surface band can mediate RKKY interactions with distinctive oscillations, differing from previous models requiring bulk or multiple surface states.

Findings

Peculiar oscillations in RKKY interaction serve as surface state signals.

Surface band effects can be individually controlled or compete, affecting magnetic behavior.

Finite Fermi energy induces additional oscillation patterns.

Abstract

Recently, abundant transport phenomena characterizing the surface states of Weyl semimetals (WSMs) have been reported. To generate these phenomena, electrons have to complete a closed intersurface orbit. Due to the unavoidable impurities in real materials, this orbit would be destroyed by the impurity scattering, which limits the detection of the surface states in WSMs. Here, we investigate the RKKY interaction between magnetic impurities, solely mediated by a single surface band, in semi-infinite WSMs. It is found that peculiar oscillations and slowly decaying laws of the RKKY interaction can act as the signals to capture the dispersive nature of the surface states of WSMs. The underlying physics is attributed to two effects: the band-edge effect and the bending effect of the surface band, which can control the RKKY interaction individually or compete with each other to produce more complex magnetic behaviors. In addition, the band-edge effect together with the finite Fermi energy would result in another interesting oscillation with battering pattern. All the results are significantly different from that in previous literatures where surface states have to couple with bulk states (or other surface states of different spins) to generate nonzero magnetic interaction. Compared to the previous models of surface states, the model here is more practical and is helpful for the deeper understanding of the surface magnetic properties in WSMs.