Tunneling resonances in superconducting single-layer NbSe2 as evidence for competing pairing channels

While bulk 2H-NbSe2 is generally accepted to be a conventional superconductor, several unconventional features of the superconducting state have been reported in the monolayer limit, including the breaking of threefold symmetry in magnetotransport and anomalously large in-plane critical fields. In this talk, I will first present another unconventional feature: the existence of satellite peaks in the STM spectra of NbSe2 monolayers which exist only in the superconducting state. After discussing potential candidate explanations, I will propose a scenario of competing pairing between s-wave and subleading f-wave triplet channels to address the different experimental observations.