Abstract
We consider a system of stacked tunnel-coupled two-dimensional electron- and hole-gas layers with Rashba spin-orbit interactions subjected to a staggered Zeeman field. The interplay of different intra-layer tunnel couplings results in a phase transition to a topological insulator phase in three dimensions hosting gapless surface states. The staggered Zeeman field further enriches the topological phase diagram by generating a second-order topological insulator phase hosting gapless hinge states. The emergence of the topological phases is proven analytically in the regime of small Zeeman field and confirmed by numerical simulations in the non-perturbative region of the phase diagram. The topological phases are stable against external perturbations and disorder.
Highlights
Over the last decade, topological insulators and superconductors (TIs) have attracted a lot of attention in the domain of condensed matter physics [1,2,3,4,5]
In this work we considered a system of coupled Rashba layers subjected to a staggered Zeeman field
Focusing on the low-energy degrees of freedom associated with the surface states, we calculated perturbatively the effect of the Zeeman term
Summary
Topological insulators and superconductors (TIs) have attracted a lot of attention in the domain of condensed matter physics [1,2,3,4,5]. Different Rashba layers are tunnel coupled to each other, and the whole heterostructure is subjected to a staggered Zeeman field. We assume that the sign of the Zeeman splitting alternates between the Rashba layers with electronand holelike dispersions. Such a staggered effective Zeeman field can be achieved in several ways. A second possibility consists of using magnetic impurities which order ferromagnetically within the same Rashba layers but have a staggered magnetization direction in different layers [47,48,49,50,51] Another option is to use thin ferromagnetically ordered layers, contained between the 2DEGs with the same dispersions. We will present the solution of the problem described by the Hamiltonian H
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