The spectral fingerprint of the enhanced surface superconducting gap in β–Bi₂Pd

Topological superconductors are attracting a majority of attentions and inspired community to investigate the candidate materials. The recent discovery of enhanced surface superconducting gap and zero bias conductance peak in β-Bi₂Pd thin film by STM [1] provides a possibility to get higher T_c topological superconductor. But the driving force behind the enhanced superconductivity is still under debate. We grown the β-Bi₂Pd thin film by MBE system and detect using in-situ angle resolved photoemission spectroscopy. We observed quantum well bands due to the high quality of the grown thin film. More importantly, we clearly distinguished the bulk band and surface band in momentum space. In the surface band, we detected the spectral fingerprint of the enhance superconducting gap.

Reference
[1]Y. F. Lv et al., Science Bulletin 62(12), 852 (2017)