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Shikin, A. M.*; Estyunin, D. A.*; Klimovskikh, I. I.*; Filnov, S. O.*; Kumar, S.*; Schwier, E. F.*; 宮本 幸治*; 奥田 太一*; 木村 昭夫*; 黒田 健太*; et al.
Scientific Reports (Internet), 10, p.13226_1 - 13226_13, 2020/08
被引用回数:48 パーセンタイル:96.27(Multidisciplinary Sciences)Modification of the gap at the Dirac point (DP) in axion antiferromagnetic topological insulator MnBiTe and its electronic and spin structure have been studied by angle- and spin-resolved photoemission spectroscopy (ARPES) under laser excitation at various temperatures, light polarizations and photon energies. We have distinguished both large and reduced gaps at the DP in the ARPES dispersions, which remain open above the Nel temperature of = 24.5 K. We propose that the gap above remains open due to a short-range magnetic field generated by chiral spin fluctuations. Spin-resolved ARPES, XMCD and circular dichroism ARPES measurements show a surface ferromagnetic ordering for the large gap sample and apparently significantly reduced effective magnetic moment for the reduced gap sample.
Shikin, A. M.*; Estyunin, D. A.*; Surnin, Yu. I.*; Koroleva, A. V.*; Shevchenko, E. V.*; Kokh, K. A.*; Tereshchenko, O. E.*; Kumar, S.*; Schwier, E. F.*; 島田 賢也*; et al.
Scientific Reports (Internet), 9(1), p.4813_1 - 4813_17, 2019/03
被引用回数:19 パーセンタイル:71.98(Multidisciplinary Sciences)A new kind of magnetically-doped antiferromagnetic (AFM) topological insulators (TIs), BiGdSbTe, has been studied by angle-resolved photoemission, superconducting magnetometry (SQUID) and X-ray magnetic circular dichroism (XMCD). It has been shown that this TI is characterized by the Dirac gap at the Fermi level. In the paramagnetic phase, a surface magnetic layer is supposed to develop, where the coupling between the Gd magnetic moments is mediated by the topological surface states (TSSs). This assumption can be confirmed by opening a gap at the Dirac point indicated by the surface-sensitive ARPES, a weak hysteresis loop measured by SQUID, the XMCD showing a surface magnetic moment and the temperature dependence of electrical resistance demonstrating a mid-gap semiconducting behavior, which correlates with the temperature dependence of the surface magnetization and confirms the conclusion that only TSSs are located at the Fermi level.
Shikin, A. M.*; Varykhalov, A.*; Prudnikova, G. V.*; Usachov, D.*; Adamchuk, V. K.*; 山田 洋一; Riley, J. D.*; Rader, O.*
Physical Review Letters, 100(5), p.057601_1 - 057601_4, 2008/02
被引用回数:71 パーセンタイル:90.25(Physics, Multidisciplinary)スピン-軌道相互作用は、強磁性体や、外部磁場を必要とせず、電子状態のスピン分裂を生じさせる。われわれはW(110)上のAu及びAgの単原子層において、顕著にスピン分裂した表面電子状態を作製した。スピン分裂は表面単原子層を構成する元素の原子量によらず、基板に依存することを明らかにした。本研究では、角度分解、及びスピン分解の光電子分光によるフェルミ面計測から、表面原子層の電子状態が、スピンに依存した基板-原子層の電子状態の混成を介して、スピン分極に至ることを明らかにした。