论文标题
Dirac Gap调制的性质和轴抗铁磁拓扑绝缘子MNBI $ _2 $ TE $ _4 $
Nature of the Dirac gap modulation and surface magnetic interaction in axion antiferromagnetic topological insulator MnBi$_2$Te$_4$
论文作者
论文摘要
在反铁磁（AFM）轴承拓扑绝缘子MNBI $ _2 $ _2 $ _4 $及其电子和旋转结构中，通过角度和自旋分辨光发射光谱（ARPE）研究了，在激发温度的变化下，通过角度和自旋分辨光光度光谱（ARPE）进行了研究（9-355〜K），磁性（9-355〜K），修改dirac Point（DP）的间隙（DP）的修改。我们在ARPES分散剂中的DP处区分了一个大的（62-67〜MEV）和减少（15-18〜MEV）的间隙，该间隙保持在Néel温度以上（$ T_ \ Mathrm {n} = 24.5 $ 〜K）。我们建议，由于手性旋转波动产生的短距离磁场，高于$ t_ \ mathrm {n} $上方的间隙保持开放。自旋分辨的ARPE，XMCD和圆形二色性ARPES测量显示了大间隙样品的表面铁磁有序，并显着降低了减少间隙样品的有效磁矩。由于结构缺陷和机械干扰，这些影响可能与拓扑DC状态向第二MN层的转移有关，在该磁性缺陷和机械干扰受到相反磁矩的补偿效果的影响。
Modification of the gap at the Dirac point (DP) in antiferromagnetic (AFM) axion topological insulator MnBi$_2$Te$_4$ and its electronic and spin structure has been studied by angle- and spin-resolved photoemission spectroscopy (ARPES) under laser excitation with variation of temperature (9-35~K), light polarization and photon energy. We have distinguished both a large (62-67~meV) and a reduced (15-18~meV) gap at the DP in the ARPES dispersions, which remains open above the Néel temperature ($T_\mathrm{N}=24.5$~K). We propose that the gap above $T_\mathrm{N}$ remains open due to short-range magnetic field generated by chiral spin fluctuations. Spin-resolved ARPES, XMCD and circular dichroism ARPES measurements show a surface ferromagnetic ordering for large-gap sample and significantly reduced effective magnetic moment for the reduced-gap sample. These effects can be associated with a shift of the topological DC state towards the second Mn layer due to structural defects and mechanical disturbance, where it is influenced by a compensated effect of opposite magnetic moments.
