Proximity-induced topological state in graphene

Abstract

The appearance of topologically protected states at the surface of an ordinary insulator is a rare occurrence and to date only a handful of materials are known for having this property. An intriguing question concerns the possibility of forming topologically protected interfaces between different materials. Here we propose that a topological phase can be transferred to graphene by proximity with the three-dimensional topological insulator Bi 2 Se 3 . By using density functional and transport theory, we prove that, at the verge of the chemical bond formation, a hybrid state forms at the graphene/Bi 2 Se 3 interface. The state has Dirac-cone-like dispersion at the point and a well defined helical spin texture, indicating its topologically protected nature. This demonstrates that proximity can transfer the topological phase from Bi 2 Se 3 to graphene.

Current-Induced Spin Polarization in Topological Insulator–Graphene Heterostructures

“…By contrast, the injection of a net spin current from a TI into a nearby spin channel material, while theoretically predicted 23 , has not yet been experimentally realized. According to theoretical studies, combining a 3D TI with a suitable 2D material such as graphene could enable transferring topological insulator properties across the interface, which might prove useful for engineering novel types of spintronic devices [24][25][26] .…”

Bismuth iron garnet Bi3Fe5O12: A room temperature magnetoelectric material

“…In a more general way, the ME coupling and electric polarization are expected in magnetically inhomogeneous structures [43], such as for example domain walls, or under nonuniform magnetic fields [32]. The micromagnetic structure of a garnet film can be influenced by an electric field, as has been shown by Logginov et al [37,38].…”

“…Linear magnetoelectric coupling is forbidden in garnets due to symmetry considerations [29][30][31][32]. Garnets are thought to preserve their centrosymmetric lattice even under epitaxial strain induced in thin films by substrates.…”

“…First of all, the linear ME effect is systematically observed in garnets with a partial cation substitution on different sublattices: (BiX)3(FeGa)5O12, where X = Lu, Y or YLaPr [37,38,40]. The non-uniform distribution of cations affects the cubic symmetry and can, in principle, give rise to the appearance of ME coupling and electric polarization [32]. Recent theoretical work [41] suggests that the lack of space inversion in the dodecahedral magnetic ion sublattice allows ferroelectric ordering in garnets.…”

2D Hybrid Nanostructured Dirac Materials for Broadband Transparent Electrodes

“…Graphene, a single layer of sp 2 ‐bonded carbon atoms, has a honeycomb lattice structure with the lattice constant a = 2.46 Å, and the hexagonal periodicity of the (0001) surface d = 4.26 Å. Although the lattice mismatch is 2.9% between graphene and Bi 2 Se 3 , the use of van der Waals epitaxy may efficiently relax the lattice‐matching condition and facilitate the large‐scale production of Bi 2 Se 3 /graphene hybrid nanostructures . Importantly, defective graphene boundaries have enhanced chemical reactivity to easily absorb heteroatoms during van der Waals epitaxy .…”