Spin and Angle-Resolved photoemission investigations on the spin texture of magnetically modified topological surface states

Our previous investigations into the electronic properties of rare-earth (RE) materials deposited 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) and Dysprosium (Dy) dopants on Bi2Se2Te 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 signatures of time-reversal symmetry breaking induced by the RE magnetic impurities. This study marks the first experimental work fully conducted at the LOREA beam-line (B. Muñiz Cano et al., Nano Lett. 2023 23, 13, 6249). If our hypothesis holds true, the observed phenomena will 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. These findings suggest the potential of these systems as a platform for enhancing spin transport properties. Therefore, unraveling the RE-induced TSS spin texture is crucial for a comprehensive understanding of the underlying physical phenomena.