Giant Rashba splitting in PtTe/PtTe heterostructure.

Achieving a large spin splitting is highly desirable for spintronic devices, which often requires breaking of the inversion symmetry. However, many atomically thin films are centrosymmetric, making them unsuitable for spintronic applications. Here, we report a strategy to achieve inversion symmetry breaking from a centrosymmetric transition metal dichalcogenide (TMDC) bilayer PtTe, leading to a giant Rashba spin splitting. Specifically, the thermal annealing turns one layer of PtTe sample into a transition metal monochalcogenide (TMMC) PtTe through Te extraction, thus forming PtTe/PtTe heterostructure with inversion symmetry breaking. In this naturally-formed PtTe/PtTe heterostructure, we observe a giant Rashba spin splitting with Rashba coefficient of α = 1.8 eV ⋅ Å, as revealed by spin- and angle-resolved photoemission spectroscopy measurements. Our work demonstrates a convenient and effective pathway for achieving pronounced Rashba splitting in centrosymmetric TMDC thin films by creating TMMC/TMDC heterostructure, thereby extending their potential applications to spintronics.