Tolerance of Topological Surface States towards Magnetic Moments: Fe onBi2Se3

Abstract

Topological insulators 1-8 are a novel form of matter which features metallic surface states with quasirelativistic dispersion similar to graphene 9 . Unlike graphene, the locking of spin and momentum and the protection by time-reversal symmetry 1-8 open up tremendous additional possibilities for external control of transport properties 10-18 .Here we show by angle-resolved photoelectron spectroscopy that the topological surface states of Bi 2 Te 3 and Bi 2 Se 3 are stable against the deposition of Fe without opening a band gap. This stability extends to low submonolayer coverages meaning that the band gap reported recently 19 for Fe on Bi 2 Se 3 is incorrect as well as to complete monolayers meaning that topological surface states can very well exist at interfaces with ferromagnets in future devices.

Ripple-modulated electronic structure of a 3D topological insulator

“…Although bulk doping is difficult to manipulate, using surface dopants shown to result in global chemical potential shifts [10][11][12][13] remains a possible option. However, this method is not ideal for various reasons: First, surface doping has been shown to create multiple topologically trivial surface states that can complicate measurements [10][11][12][13] . Second, although doping can be used to create large changes in the spatially averaged chemical potential, using this method to manipulate the local potential is non-trivial 14 .…”

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

“…Generally speaking, the TI boundary states have a rather wide range of tunability of the electronic properties under various perturbations, such as structural distortions [10,11] and mechanical strains [12,13], adsorption of (magnetic and nonmagnetic) atoms and molecules on the surface [14][15][16][17], an alternation of the surface termination [18,19], engineering via capping layers and interfaces with other materials [20][21][22][23], applying an external gate voltage [20,24,25], etc., some of which are accompanied by electrostatic bending of actual bands in TIs. We only briefly annotate the interesting consequences of these perturbations for the states confined at the TI boundary (of course, our literature survey is not exhaustive).…”

Signatures of Dirac fermion-mediated magnetic order

“…Results published so far seem to suggest that surface-and bulk-doped samples behave quite differently. Namely, an opening of the Dirac gap with the onset of magnetic order was exclusively reported for bulk-doped samples 16,18 , while the Dirac cone remained intact for most studies employing surface doping [22][23][24][25] . This is in contradiction to the theory which predicts that, because of the absence of scattering into the bulk, surfaceconfined Dirac fermions can mediate magnetic interaction over distances of several nanometres via the Ruderman-KittelKasuya-Yosida (RKKY) interaction 26,27 .…”

“…Although numerous studies aimed to shed light on the role played by magnetic perturbations, contradictory results have been obtained and a clear picture is still missing [16][17][18][19][20][21][22][23][24][25] . Results published so far seem to suggest that surface-and bulk-doped samples behave quite differently.…”