Nonmagnetic band gap at the Dirac point of the magnetic topological insulator (Bi(1-x)Mn(x))2Se3.
Nonmagnetic band gap at the Dirac point of the magnetic topological insulator (Bi(1-x)Mn(x))2Se3.
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DOI：
10.1038/ncomms10559
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发表时间：
2016-02-19
影响因子：
16.6
通讯作者：
Rader O
中科院分区：
文献类型：
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作者：
Sánchez-Barriga J;Varykhalov A;Springholz G;Steiner H;Kirchschlager R;Bauer G;Caha O;Schierle E;Weschke E;Ünal AA;Valencia S;Dunst M;Braun J;Ebert H;Minár J;Golias E;Yashina LV;Ney A;Holý V;Rader O
磁掺杂有望通过打破时间反转对称性在拓扑绝缘体的狄拉克点打开带隙，并实现新的拓扑相。外延 (Bi1−xMnx)2Se3 是一种典型的磁拓扑绝缘体，其表面带隙约为 100 meV。我们表明，这个间隙既不是由于本体或表面的铁磁有序，也不是由于 Mn 的局部磁矩，使得该系统不适合实现新相。我们进一步表明，Mn 掺杂不会影响倒置体带隙，并且系统在拓扑上仍然不平凡。我们认为强共振散射过程会导致狄拉克点处的间隙，并通过使用共振光发射观察间隙内状态来支持这一点。我们的研究结果建立了一种在拓扑表面态中打开间隙的机制，这挑战了当前已知的拓扑保护条件。 用磁性杂质掺杂拓扑绝缘体预计会诱发铁磁性并在其表面态中打开带隙。在这里，作者研究了锰掺杂的 Bi2Se3，找到了一种在非磁性起源的拓扑保护表面态中打开带隙的机制。
Magnetic doping is expected to open a band gap at the Dirac point of topological insulators by breaking time-reversal symmetry and to enable novel topological phases. Epitaxial (Bi1−xMnx)2Se3 is a prototypical magnetic topological insulator with a pronounced surface band gap of ∼100 meV. We show that this gap is neither due to ferromagnetic order in the bulk or at the surface nor to the local magnetic moment of the Mn, making the system unsuitable for realizing the novel phases. We further show that Mn doping does not affect the inverted bulk band gap and the system remains topologically nontrivial. We suggest that strong resonant scattering processes cause the gap at the Dirac point and support this by the observation of in-gap states using resonant photoemission. Our findings establish a mechanism for gap opening in topological surface states which challenges the currently known conditions for topological protection. Doping a topological insulator with magnetic impurities is expected to induce ferromagnetism and open a band gap in its surface states. Here, the authors study Mn-doped Bi2Se3, finding a mechanism for band gap opening in topologically-protected surface states which is not of magnetic origin.