Spatial anisotropy of the Kondo screening cloud in a type-II Weyl semimetal

Article

关键词: TOPOLOGICAL DIRAC SEMIMETAL;    FERMI ARCS;    DISCOVERY;   

DOI  :  10.1103/PhysRevB.99.235108

来源: SCIE

【 摘 要 】

We theoretically study the Kondo screening of a spin-1/2 magnetic impurity in the bulk of a type-II Weyl semimetal (WSM) by use of the variational wave-function method. We consider a type-II WSM model with two Weyl nodes located on the k(z) axis, and the tilting of the Weyl cones are along the k(x) direction. Due to coexisting electron and hole pockets, the density of states at the Fermi energy becomes finite, leading to a significant enhancement of the Kondo effect. Consequently, the magnetic impurity and the conduction electrons always form a bound state; this behavior is distinct from that in type-I WSMs, where the bound state is only formed when the hybridization exceeds a critical value. Meanwhile, the spin-orbit coupling and unique geometry of the Fermi surface lead to a strongly anisotropic Kondo screening cloud in coordinate space. The tilting terms break the rotational symmetry of the type-II WSM about the k(z) axis, but the system remains invariant under a combined transformation tau R-y(pi), where tau is the time-reversal operation and R-y(pi) is the rotation about the y axis by pi. Largely modified diagonal and off-diagonal components of the spin-spin correlation function on three principal planes reflect this change in band symmetry. Most saliently, on the x-z plane, tilting terms trigger the emergence of nonzero off-diagonal spin-spin correlation function J(yz) (r) and J(xy)(r), while in a type-I WSM they vanish on the x-z plane.

【 授权许可】

Free