Abstract
Three-dimensional materials with strong spin–orbit coupling and magnetic interactions represent an opportunity to realize a variety of rare and potentially useful topological phases with broken time-reversal symmetry. In this work, we use first principles calculations to show that the recently synthesized material Bi2MnSe4 displays a combination of spin–orbit-induced band inversion, also observed in non-magnetic topological insulator Bi2PbSe4, with magnetic interactions, leading to several topological phases. In bulk form, the ferromagnetic phase of Bi2MnSe4 has symmetry protected band crossings at the Fermi level, leading to either a nodal line or Weyl semimetal, depending on the direction of the spins. Due to the combination of time reversal symmetry plus a partial translation, the ground state layered antiferromagnetic phase is instead an antiferromagnetic topological insulator. The surface of this phase intrinsically breaks time-reversal symmetry, allowing the observation of the half-integer quantum anomalous Hall effect. Furthermore, we show that in thin film form, for sufficiently thick slabs, Bi2MnSe4 becomes a Chern insulator with a band gap of up to 58 meV. This combination of properties in a stoichiometric magnetic material makes Bi2MnSe4 an excellent candidate for displaying robust topological behavior.
Highlights
Since the discovery of time-reversal invariant (Z2) topological insulators[1–4] a decade ago, there has been a major increase in interest in topological condensed matter systems, due to both scientific interest and potential applications.[4–10] Despite these efforts, it remains challenging to find robust materials with realizations of many phases, especially those with broken time reversal symmetry (TRS)
We find that depending on the symmetry of the magnetic ordering and the sample thickness, Bi2MnSe4 can access many different topological phases with broken TRS: a nodal line system, magnetic Weyl semimetal, AFM topological insulator, or Chern insulator, in addition to displaying the half-integer quantum anomalous Hall effect (AHC)
We study the topological behavior of Bi2MnSe4
Summary
Since the discovery of time-reversal invariant (Z2) topological insulators[1–4] a decade ago, there has been a major increase in interest in topological condensed matter systems, due to both scientific interest and potential applications.[4–10] Despite these efforts, it remains challenging to find robust materials with realizations of many phases, especially those with broken time reversal symmetry (TRS). Since the discovery of time-reversal invariant (Z2) topological insulators[1–4] a decade ago, there has been a major increase in interest in topological condensed matter systems, due to both scientific interest and potential applications.[4–10]. Despite these efforts, it remains challenging to find robust materials with realizations of many phases, especially those with broken time reversal symmetry (TRS). Current quantum anomalous Hall materials, based on magnetically doped topological insulators,[13,14–17] are limited to very low temperatures (~1 K),[13] but there is no intrinsic reason for this limit, and there remains significant interest[18–23] in finding Chern insulators with larger band gaps and higher magnetic ordering temperatures.[23–28]. Weyl semimetals (WSM)[29–31] are materials with topologically protected linearly dispersing band crossings, known as
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