Tunable correlation effects of magnetic impurities by cubic Rashba spin-orbit coupling

We theoretically study the influence of the k-cubic Rashba spin-orbit coupling (SOC) on the correlation effects of magnetic impurities by combining the variational method and the Hirsch-Fye quantum Monte Carlo (HFQMC) simulations. Markedly different from the normal k-linear Rashba SOC, even a small cubic Rashba term can greatly alter the band structure and induce a Van Hove singularity in a wide range of energy; thus, the single impurity local moment becomes largely tunable. The cubic Rashba SOC adopted in this paper breaks the rotational symmetry, but the host material is still invariant under the operations Rz(pi), IRz(pi /2), Mxz, Myz, where Rz(theta) is the rotation of angle theta about the z axis, I is the inversion operator, and Mxz (Myz) is the mirror reflection about the x-z (y-z) principal plane. Saliently, various components of spin-spin correlation between the single magnetic impurity and the conduction electrons show three- or sixfold rotational symmetry. This unique feature is due to the triple winding of the spins with a 2 pi rotation of k, which is a hallmark of the cubic Rashba effect, and can possibly be an identifier to distinguish the cubic Rashba SOC from the normal k-linear Rashba term in experiments. Although the cubic Rashba term drastically alters the electronic properties of the host, we find that the spatial decay rate of the spin-spin correlation function remains essentially unchanged. Moreover, the carrier-mediated Ruderman-Kittel-Kasuya-Yosida interactions between two magnetic impurities show twisted features, the ferromagnetic diagonal terms dominate when two magnetic impurities are very close, but the off-diagonal terms become important at long distances.

Automated summary

In this study, we investigate the correlation effects of magnetic impurities influenced by the k-cubic Rashba spin-orbit coupling (SOC) using the variational method and Hirsch-Fye quantum Monte Carlo simulations. We find that even a small cubic Rashba term can significantly modify the band structure and induce a Van Hove singularity, leading to tunable single impurity local moments. The spin-spin correlation between the magnetic impurity and conduction electrons exhibits unique three- or sixfold rotational symmetry due to the triple winding of spins with a 2 pi rotation of k, which distinguishes the cubic Rashba SOC from the normal k-linear Rashba term. Additionally, we observe twisted features in the carrier-mediated Ruderman-Kittel-Kasuya-Yosida interactions between two magnetic impurities, with ferromagnetic diagonal terms dominating at close distances and important off-diagonal terms at long distances.