论文标题
富含Mn
Mn-rich MnSb2Te4: A topological insulator with magnetic gap closing at high Curie temperatures of 45-50 K
论文作者
论文摘要
铁磁拓扑绝缘子表现出量子异常的效果，可用于高精度计量学和边缘通道旋转。与超导体结合使用，它们可以主持手性少量零模式，这是实现拓扑量表的竞争者之一。最近，发现MN的稳定2+状态可以用A1B2C4化学计量形成固有的磁性绝缘体。然而，第一个代表性MNBI2TE4是抗磁磁性的，温度为25 knéel温度，并且浓烈地掺杂。在这里，我们表明，以前被认为是拓扑的P型MNSB2TE4在MN过量的百分之几中是铁磁拓扑绝缘子。 It shows (i) a ferromagnetic hysteresis with record high Curie temperature of 45-50 K, (ii) out-of-plane magnetic anisotropy and (iii) a two-dimensional Dirac cone with the Dirac point close to the Fermi level which features (iv) out-of-plane spin polarization as revealed by photoelectron spectroscopy and (v) a magnetically induced band gap that closes at the Curie temperature as通过扫描隧道光谱法证明。此外，它显示（vi）磁化β〜1的关键指数，表明量子临界点的附近。从头算结构的计算表明，替代SB原子的MN略有过量提供了铁磁层间偶联。剩余的与铁磁阶的偏差可能与此替代有关，打开倒数散装带隙并渲染MNSB2TE4稳健的拓扑绝缘子和用于磁性拓扑绝缘子的新基准。
Ferromagnetic topological insulators exhibit the quantum anomalous Hall effect that might be used for high precision metrology and edge channel spintronics. In conjunction with superconductors, they could host chiral Majorana zero modes which are among the contenders for the realization of topological qubits. Recently, it was discovered that the stable 2+ state of Mn enables the formation of intrinsic magnetic topological insulators with A1B2C4 stoichiometry. However, the first representative, MnBi2Te4, is antiferromagnetic with 25 K Néel temperature and strongly n-doped. Here, we show that p-type MnSb2Te4, previously considered topologically trivial, is a ferromagnetic topological insulator in the case of a few percent of Mn excess. It shows (i) a ferromagnetic hysteresis with record high Curie temperature of 45-50 K, (ii) out-of-plane magnetic anisotropy and (iii) a two-dimensional Dirac cone with the Dirac point close to the Fermi level which features (iv) out-of-plane spin polarization as revealed by photoelectron spectroscopy and (v) a magnetically induced band gap that closes at the Curie temperature as demonstrated by scanning tunneling spectroscopy. Moreover, it displays (vi) a critical exponent of magnetization beta~1, indicating the vicinity of a quantum critical point. Ab initio band structure calculations reveal that the slight excess of Mn that substitutionally replaces Sb atoms provides the ferromagnetic interlayer coupling. Remaining deviations from the ferromagnetic order, likely related to this substitution, open the inverted bulk band gap and render MnSb2Te4 a robust topological insulator and new benchmark for magnetic topological insulators.
