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arXiv · 1309.6676

Fully gapped topological surface states in Bi$_2$Se$_3$ films induced by a d-wave high-temperature superconductor

Eryin Wang·Hao Ding·Alexei V. Fedorov·Wei Yao·Zhi Li·Yan-Feng Lv·Kun Zhao·Li-Guo Zhang·Zhijun Xu·John Schneeloch·Ruidan Zhong·Shuai-Hua Ji·Lili Wang·Ke He·Xucun Ma·Genda Gu·Hong Yao·Qi-Kun Xue·Xi Chen·Shuyun Zhou
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Abstract

Topological insulators are a new class of materials, that exhibit robust gapless surface states protected by time-reversal symmetry. The interplay between such symmetry-protected topological surface states and symmetry-broken states (e.g. superconductivity) provides a platform for exploring novel quantum phenomena and new functionalities, such as 1D chiral or helical gapless Majorana fermions, and Majorana zero modes which may find application in fault-tolerant quantum computation. Inducing superconductivity on topological surface states is a prerequisite for their experimental realization. Here by growing high quality topological insulator Bi$_2$Se$_3$ films on a d-wave superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ using molecular beam epitaxy, we are able to induce high temperature superconductivity on the surface states of Bi$_2$Se$_3$ films with a large pairing gap up to 15 meV. Interestingly, distinct from the d-wave pairing of Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$, the proximity-induced gap on the surface states is nearly isotropic and consistent with predominant s-wave pairing as revealed by angle-resolved photoemission spectroscopy. Our work could provide a critical step toward the realization of the long sought-after Majorana zero modes.

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Eryin Wang, Hao Ding, Alexei V. Fedorov, Wei Yao, Zhi Li, Yan-Feng Lv, Kun Zhao, Li-Guo Zhang, Zhijun Xu, John Schneeloch, Ruidan Zhong, Shuai-Hua Ji, Lili Wang, Ke He, Xucun Ma, Genda Gu, Hong Yao, Qi-Kun Xue, Xi Chen, Shuyun Zhou. 2013-09-27. Fully gapped topological surface states in Bi$_2$Se$_3$ films induced by a d-wave high-temperature superconductor. https://doi.org/10.1038/nphys2744

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