Complex Spin Texture in the Pure and Mn-Doped Topological InsulatorBi2Te3

Abstract

Topological insulators are characterized by the presence of spin-momentum-locked surface states with Dirac points that span the fundamental bulk band gap. We show by first-principles calculations that the surface state of the insulator Bi 2 Te 3 survives upon moderate Mn doping of the surface layers. The spin texture of both undoped and Mn-doped Bi 2 Te 3 is much more complicated than commonly believed, showing layer-dependent spin reversal and spin vortices.

Infrared electrodynamics and ferromagnetism in the topological semiconductorsBi2Te3and Mn-dopedBi2Chapler1, Post2, Richardella3 et al. 2014Phys. Rev. B243260View full textAdd to dashboardCite

“…For instance, it remains to be seen if upon transition metal doping, TIs can retain their topological SSs to achieve a gap at the Dirac point. It is theoretically anticipated that this is indeed possible 5,[19][20][21] . Experimentally, however, while SSs have been observed in ferromagnetic transition metal-doped TI hosts, they are significantly broadened and not well defined compared to pure samples 12,18 .…”

Experimental and density functional study of Mn doped Bi2Te3 topological insulator

“…All evaporation materials used were of 99.9999% purity and the films were deposited in a Te-rich environment to reduce the formation of Bi-Te anti-site defects and Te vacancies. Growing with a Bi:Te flux ratio of 1:10, the deposition rate is Bi-limited at ∼0.4 nm min 1 . Nominal Mn-doping concentrations were adjusted using the Mn:Bi flux ratio, as measured by the BFM.…”

“…1 TIs are insulating in their bulk. However, their surface states are gapless and protected by time-reversal symmetry (TRS) which makes them immune to backscattering from disorder and non-magnetic impurities.…”

Observation of Distinct Bulk and Surface Chemical Environments in a Topological Insulator under Magnetic Doping

“…The evidence for long range ferromagnetism in TIs is primarily based upon bulk sensitive techniques, and clear results distinguishing between surface and bulk properties are scarce. In TIs, a thickness dependent evolution of the spin and band structure exists 14,15 . As such, the critical thickness for the appearance of topological conditions (i.e.…”