Interface-induced states at the boundary between a 3D topological insulator and a normal insulator

Band bending driven evolution of the bound electron states at the interface between a three-dimensional topological insulator and a three-dimensional normal insulator

“…Following the method described in Ref. [9] the equations for the envelope function on the TI side can be expressed in compact form as…”

“…[9,31]. The relevant theoretical model is based on the four-band k · p Hamiltonian with strong SOC proposed in Ref.…”

“…[9], we use a simple variational approach and formally introduce an effective intermixing of electron states of the contacting TI and NI materials at the interface. The intermixing is simulated by an effective potential of hybridization V N (r) between the states | ± ,↑↓ and |N,↑↓ specified by the eigen Bloch functions of the TI bulk and NI bulk, respectively, which are declared to be associated with different crystal symmetries.…”

“…Recently, in Ref. [9], this phenomenon has been preliminarily studied with an analytical approach. Within a quasiparticle concept it was demonstrated that the spectrum of interfacial bound electron states contains "ordinary" and "topological" branches with different characteristic lengths, probability maxima, and peaks of spectral weight in the energy scale.…”

“…The analytical description in Ref. [9] was based on the simplified model of an effective short-range interface (pseudo)potential provided by hybridization of the TI and NI electron states at the TI/NI interface. It was predicted that, even within this model, interfacial bound electron states exist near the TI/NI boundary.…”