Broken Inversion Symmetry and Interface-induced Spin-polarization for metal-Weyl semimetal stacked interfaces

Abstract

Weyl semimetal TaAs, a congenial host to the massless Weyl fermions, spontaneously lacks the time-reversal and the inversion symmetry and thus effectuates topologically stable Weyl nodes, resembling magnetic monopoles in momentum space. Former experimental analysis had revealed that the near-zero spin-polarization of bulk TaAs experiences a boost in presence of point-contacts of non-magnetic metals along with the associated phenomena of tip-induced superconductivity, providing the impetus to study the large-area stacked interfaces of TaAs with Noble metals like Au and Ag. First-principles calculations on these interfacial systems have manifested an increment of the interface-induced spin-polarization and contact-induced transport spin-polarization. In contrast to the single interface, for stacked system, the broken inversion symmetry of the system introduces a z-directional band-dispersion resulting in an energetically separated series of Weyl cones. The Weyl cones for TaAs/Ag and TaAs/Au stacked interfaces are observed to be of type-I and type-II nature respectively. Thus, the current study demonstrates the designing of two different types of spin-polarized Weyl systems from non-magnetic metal and type I Weyl components.