Nature of the Dirac gap modulation and surface magnetic interaction in axion antiferromagnetic topological insulator MnBiTe

アクシオン反強磁性トポロジカル絶縁体MnBiTeにおけるディラックギャップ変調と表面磁気相互作用の特質

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*; 矢治 光一郎*; Shin, S.*; 竹田 幸治   ; 斎藤 祐児  ; Aliev, Z. S.*; Mamedov, N.*; Amiraslanov, I. R.*; Babanly, M. B.*; Otrokov, M. M.*; Eremeev, S. V.*; Chulkov, E. V.*

Shikin, A. M.*; Estyunin, D. A.*; Klimovskikh, I. I.*; Filnov, S. O.*; Kumar, S.*; Schwier, E. F.*; Miyamoto, Koji*; Okuda, Taiichi*; Kimura, Akio*; Kuroda, Kenta*; Yaji, Koichiro*; Shin, S.*; Takeda, Yukiharu; Saito, Yuji; Aliev, Z. S.*; Mamedov, N.*; Amiraslanov, I. R.*; Babanly, M. B.*; Otrokov, M. M.*; Eremeev, S. V.*; Chulkov, E. V.*

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.