Interplay between Mn-acceptor state and Dirac surface states in Mn-dopedBi2Se3topological insulator

Abstract

We investigate the properties of a single substitutional Mn impurity and its associated acceptor state on the (111) surface of Bi 2 Se 3 topological insulator. Combining ab initio calculations with microscopic tight-binding modeling, we identify the effects of inversion symmetry and time-reversal-symmetry breaking on the electronic states in the vicinity of the Dirac point. In agreement with experiments, we find evidence that the Mn ion is in the +2 valence state and introduces an acceptor in the bulk band gap. The Mn acceptor has predominantly p character and is localized mainly around the Mn impurity and its nearest-neighbor Se atoms. Its electronic structure and spin-polarization are determined by the hybridization between the Mn d levels and the p levels of surrounding Se atoms, which is strongly affected by electronic correlations at the Mn site. The opening of the gap at the Dirac point depends crucially on the quasiresonant coupling and the strong real-space overlap between the spin-chiral surface states and the midgap spin-polarized Mn-acceptor states.

Electrically tunable Dirac-point resonance induced by a nanomagnet absorbed on the topological insulator surface

“…Obviously, the bias dependence of the transition rate provides a route to electrically control P M and in turn the self-energy in Eq. (7).…”

“…2 (c), increases, which significantly modifies the self-energy (ω) in Eq. (7). At the same time, the nanomagnet is polarized as shown in Fig.…”

“…For instance, some works [4][5][6][7][8] reported that magnetic doping can destroy the Dirac point of the TSSs by opening a local gap while some others [9][10][11][12][13][14] demonstrated that the Dirac node remains immune from magnetic perturbations. More interesting is the tunneling spectrum measurement for Fe atoms with magnetic anisotropy absorbed on Bi 2 Te 3 materials [10,15], where an energy gap was not observed at the Dirac point, and instead a considerably strong resonance was found nearby.…”

“…A tremendous effort has been devoted to the robustness of the TSSs against magnetic impurities [4][5][6][7][8][9][10][11][12][13][14], but currently there is no consensus on the behavior of magnetic impurities in experimental and theoretical literatures. For instance, some works [4][5][6][7][8] reported that magnetic doping can destroy the Dirac point of the TSSs by opening a local gap while some others [9][10][11][12][13][14] demonstrated that the Dirac node remains immune from magnetic perturbations.…”

Strain-modulated ferromagnetism and band gap of Mn doped Bi2Se3

“…Experiments1820 and theoretical calculations2930 have suggested that the magnetic dopants, such as V, Cr, Mn and Fe, will mostly substitute the Bi or Sb ions in 3D TIs; we therefore concentrate on this situation. As shown in Fig.…”