摘要
Connate topological superconductor(TSC) combines topological surface states with nodeless superconductivity in a single material, achieving effective p-wave pairing without interface complication. By combining angle-resolved photoemission spectroscopy and in-situ molecular beam epitaxy, we studied the momentum-resolved superconductivity in b-Bi2 Pd film. We found that the superconducting gap of topological surface state(DTSS$ 3.8 meV) is anomalously enhanced from its bulk value(Db$ 0.8 meV). The ratio of 2 DTSS/kBTc$ 16.3, is substantially larger than the BCS value. By measuring b-Bi2 Pd bulk single crystal as a comparison, we clearly observed the upward-shift of chemical potential in the film. In addition, a concomitant increasing of surface weight on the topological surface state was revealed by our first principle calculation, suggesting that the Dirac-fermion-mediated parity mixing may cause this anomalous superconducting enhancement. Our results establish b-Bi2 Pd film as a unique case of connate TSCs with a highly enhanced topological superconducting gap, which may stabilize Majorana zero modes at a higher temperature.
Connate topological superconductor(TSC) combines topological surface states with nodeless superconductivity in a single material, achieving effective p-wave pairing without interface complication. By combining angle-resolved photoemission spectroscopy and in-situ molecular beam epitaxy, we studied the momentum-resolved superconductivity in b-Bi2 Pd film. We found that the superconducting gap of topological surface state(DTSS$ 3.8 meV) is anomalously enhanced from its bulk value(Db$ 0.8 meV). The ratio of 2 DTSS/kBTc$ 16.3, is substantially larger than the BCS value. By measuring b-Bi2 Pd bulk single crystal as a comparison, we clearly observed the upward-shift of chemical potential in the film. In addition, a concomitant increasing of surface weight on the topological surface state was revealed by our first principle calculation, suggesting that the Dirac-fermion-mediated parity mixing may cause this anomalous superconducting enhancement. Our results establish b-Bi2 Pd film as a unique case of connate TSCs with a highly enhanced topological superconducting gap, which may stabilize Majorana zero modes at a higher temperature.
基金
supported by the Ministry of Science and Technology of China, China (2016YFA0401000, 2016YFA0300600, 2015CB921000)
the National Natural Science Foundation of China, China (11888101, 11574371, 11622435, 11474340 and 11774399)
the Chinese Academy of Sciences, China (XDB28000000, XDB07000000, QYZDB-SSW-SLH043)
the Beijing Municipal Science and Technology Commission, China (Z171100002017018, Z181100004218005 and Z171100002017018)
Beijing Natural Science Foundation (Z180008)
the National Key Research and Development Program of China, China (2017YFA0302901)
supports by the Ministry of Science and Technology of China, China (2016YFA0401002)
the CAS Pioneer ‘‘Hundred Talents Program” (type C)
