Interface induced states at the boundary between a 3D topological insulator Bi2Se3 and a ferromagnetic insulator EuS

Abstract

By means of relativistic density functional theory (DFT) calculations we study electron band structure of the topological insulator (TI) Bi 2 Se 3 thin films deposited on the ferromagnetic insulator (FMI) EuS substrate. In the Bi 2 Se 3 /EuS heterostructure, the gap opened in the spectrum of the topological state has a hybridization character and is shown to be controlled by the Bi 2 Se 3 film thickness, while magnetic contribution to the gap is negligibly small. We also analyzed the effect of Eu doping on the magnetization of the Bi 2 Se 3 film and demonstrated that the Eu impurity induces magnetic moments on neighboring Se and Bi atoms an order of magnitude larger than the substrate-induced moments. Recent magnetic and magneto-transport measurements in EuS/Bi 2 Se 3 heterostructure are discussed.

Signature of gate-controlled magnetism and localization effects at Bi2Se3/EuS interface

“…5). Although the increase in R xx due to magnetic proximity is in agreement with the localization effects observed from our WAL studies, the concomitant drop in R xx at the onset of interface magnetism is not well explained based on any spin disorder or EEI models supporting WL mechanisms 16,33,50 . In Fig.…”

“…However, requirement of an out-of-plane magnetization at the TI surface makes this study difficult since most MIs naturally possess in-plane anisotropy. Also, new hybridization states 13 that may form at the TI/MI interface near the E F can contaminate the topological properties of the Dirac SSs [14][15][16] . As a result, observing these effects through transport studies can become nontrivial.…”

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

“…In a nearest vicinity of the κ = 0 point, the expression for the dispersion is described by the Dirac-conelike law E(κ) = E(0) ± vκ, where E(0) and v are the node point position and the group velocity, respectively, which are functions of the interfacial potential W (N) (8). The dependence of the Dirac point E(0) on the interfacial potential components W (N) 1,2 is given by the equation…”

“…Numerical calculations based on density functional theory (DFT) methods have shown a very unusual picture of the space and energy relocation of interfacial electron states in some TI/NI heterostructures composed of the TI and NI slabs [7,8]. The principal effect in these systems is the formation of interfacial bound electron states of two different types.…”

Interplay of Topological States on TI/TCI Interfaces

“…As can be seen from the figure, the SnBi Te SL adjacent to the interface plane demonstrates large charge redistribution and maximum charge transfer occurs on the outer Te layer. At the same time, the charge redistribution in the SnTe part of the structure is relatively small, like in case of the interface between TI and normal [ 49 ] (magnetic [ 20 , 50 ]) insulator. Such a change in the electronic charge density leads to substantial modification of the electrostatic potential at the TI/TCI interface.…”