Spin and Angle-Resolved photoemission investigations on the spin texture of topological surface states modified by Rare-Earth surface dopants.

Our previous investigations into the electronic properties of rare-earth (RE) materials depos-ited on topological insulator (TI) surfaces have unveiled intriguing and exciting phenomena within the topological surface state (TSS) electronic structure. Specifically, the deposition of magnetic Erbium (Er) rare-earth dopants on Bi2Se2Te and Bi2Te3 substrates has been found to directly impact the typical hexagonal warping of the Fermi Surface (FS) of the TSS, resulting in a change in FS symmetry from hexagonal to trigonal, accompanied by the opening of a gap at the Dirac point. These spectroscopic features have been elucidated and rationalized as signa-tures of time-reversal symmetry breaking induced by the RE magnetic impurities. This study marked the first experimental work fully conducted at the LOREA beamline (B. Muñiz Cano et al., Nano Lett., 2023 23, 13, 6249). The observed phenomena should result in the alteration of the spin texture of the TSS. By reducing the FS symmetry, channels allowing backscattering in the hexagonal warped FS would be suppressed in the trigonal phase, leading to a reduction of out-of-plane spin components of the TSS. Therefore, unraveling the RE-induced TSS spin texture is crucial for a comprehensive understanding of the underlying physical phenomena

我们此前针对沉积于拓扑绝缘体（topological insulator, TI）表面的稀土（rare-earth, RE）材料的电子特性开展的研究，在拓扑表面态（topological surface state, TSS）的电子结构中揭示了一系列引人入胜且极具研究价值的现象。具体而言，研究发现在Bi₂Se₂Te和Bi₂Te₃衬底上沉积磁性稀土掺杂剂铒（Erbium, Er）后，会直接影响拓扑表面态费米面（Fermi Surface, FS）典型的六角形翘曲特性，使费米面的对称性从六角形转变为三角晶系，同时在狄拉克点处打开能隙。这些光谱特征可被阐释为稀土磁性杂质引发时间反演对称性破缺的特征信号。本研究是首个完全在LOREA光束线开展的实验工作（B. Muñiz Cano等，《纳米快报》（Nano Lett.），2023年，第23卷第13期，第6249页）。上述观测到的现象将导致拓扑表面态的自旋结构发生改变。通过降低费米面对称性，六角形翘曲费米面中原本允许背散射的通道在三角晶系相内会被抑制，进而使拓扑表面态的面外自旋分量降低。因此，阐明稀土杂质诱导的拓扑表面态自旋结构，对于全面理解其背后的物理机制至关重要。