Topological Character and Magnetism of the Dirac State in Mn-DopedBi2Te3

Abstract

First-principles and model calculations show that the Dirac surface state of the topological insulator Bi 2 Te 3 survives upon moderate Mn doping of the surface layers but can lose its topological character as a function of magnetization direction. The dispersion depends considerably on the direction of the Mn magnetization: for perpendicular magnetization, a gap of 16 meV opens up at the Dirac point; for in-plane magnetization, a tiny gap can be opened or closed in dependence on the magnetization azimuth. The ground state is ferromagnetic, with a critical temperature of 12 K. The results provide a path towards a magnetic control of the topological character of the Dirac surface state and its consequences to spindependent transport properties.

Exchange interaction and its tuning in magnetic binary chalcogenides

“…One of the first comprehensive studies was carried out by Larson and Lambrecht [31], who investigated the electronic and magnetic properties of bulk Bi 2 Se 3 , Bi 2 Te 3 , and Sb 2 Te 3 doped with 3d transition-metal atoms; their results for magnetically doped Bi 2 Se 3 were confirmed by Yu et al [32] and Zhang et al [33]. Recently, it was shown that the Dirac surface state of the topological insulator Bi 2 Te 3 survives upon moderate Mn doping of the surface QL, but can lose its topologically nontrivial character depending on the magnetization direction [34,35]. However, critical magnetic properties and the exchange interaction behavior in magnetic binary tetradymite chalcogenides were not studied in detail on a theoretical ab initio level and, thus, are still under debate.…”

Imaging Dirac-mass disorder from magnetic dopant atoms in the ferromagnetic topological insulator Cr x (Bi 0.1 Sb 0.9 ) 2-x Te 3

“…Opening a gap in this spectrum is key to the realization of several extraordinary new types of electronic phenomena. The prevalent approach to opening this "Dirac-mass gap" is to dope the materials with magnetic atoms (1)(2)(3)(4)(5)(6). A plethora of new physics is then predicted, including σ xy = ±e 2 =h quantum anomalous Hall effects (QAHE) (7,8), topological surface-state magneto-electric effects (9)(10)(11)(12), related magneto-optical Kerr and Faraday rotations (10,13,14), axionic-like electrodynamics (15,16), and even E-field induced magnetic monopoles (17,18).…”

Understanding the Giant Enhancement of Exchange Interaction in Bi2Se3−EuS Heterostructures

“…The emergent quantum phenomena such as the topological magnetoelectric effect [4], the quantum anomalous Hall effect [1], and the large spin-orbit torque [5,6] have inspired interdisciplinary endeavors to investigate their underlying scientific principles and to explore innovative materials with nontrivial topological properties. The conventional approach that is currently used to magnetize and manipulate the TSSs is magnetic doping, with magnetic dopants such as Cr [7][8][9][10], Fe [11][12][13][14][15], and Mn [16,17] substituting the cations in TIs. Although successful observation of the quantum anomalous Hall effect has been reported for Cr-or V-doped (Bi,Sb) 2 Te 3 [18][19][20], further progress has nonetheless been impeded by various technical issues, mostly due to the uncontrollability of dopant distribution and magnetic ordering.…”