Abstract
We theoretically study the superconducting proximity effect between a topological insulator (TI) and a high-temperature -wave superconductor (dSC). When the TI-dSC heterostructure violates rotation and certain reflection symmetries, we show that a sizable -wave pairing, coexisting with a -wave one, emerges in the proximity-induced superconductivity in the TI's top surface states. Weak disorder further suppresses -wave pairing (but not -wave pairing) in the TI's surface states. More importantly, the pairing gap in the surface states is found to be nodeless and nearly isotropic when the Fermi pocket of surface states is relatively small. Our theoretical results qualitatively explain recent experimental evidences of a nearly-isotropic pairing gap on surface states of induced by proximity to high- cuprate . We also demonstrate convincing evidence of Majorana zero modes in a magnetic vortex core which may be detectable in future experiments.
- Received 1 March 2014
- Revised 1 June 2015
DOI:https://doi.org/10.1103/PhysRevB.91.235143
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