Superconductivity in Cu-intercalated Bi2Se3 Topological Superconductor
Shih-Hsun Yu1,2,3*, Min-Nan Ou3, Mitch M. C. Chou1,2, Yang-Yuan Chen3
1Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, Taiwan
2NSC Taiwan Consortium of Emergent Crystalline Materials (TCECM), National Sun Yat-Sen University, Kaohsiung, Taiwan
3Institute of Physics, Academia Sinica, Taipei, Taiwan
* presenting author:Shih-Hsun Yu, email:s4901551@gmail.com
Because of the discovery of novel quantum states and the persuade of majorana fermion, three-dimensional (3D) topological insulators (TIs) such as Bi1-xSbx alloys, Bi2Se3, Bi2Te3, and Sb2Te3 compounds [1, 2] have received much attention in recent years. Currently, Cu-doped Bi2Se3 is found to be a topological superconductor (TSC), which has been considered as a candidate of p-wave superconductor, offering a great opportunity to searching for Majorana fermions. [3, 4] In this study, Cu-intercalated Bi2Se3 single crystals are prepared by molten growth method followed by electrochemical intercalation (EC method), in which copper (Cu) atoms enter the van der Waals gaps between Bi2Se3 quintuple layers. The Cu concentration is precisely manipulated by the controls of current and reaction time during the electrochemical process. In Cu0.1Bi2Se3, a clear superconducting transition at Tc = 2.8 K with large shielding fraction (volume susceptibility) of ~ 60% is observed. With further increasing Cu content, the superconducting transition temperature will shift to lower temperature; meanwhile, the shielding fraction decreases as well. These results indicate that the Cu concentration in van der Waal gaps is a very decisive parameter for tuning the superconducting behavior in Cu-Bi2Se3 system. In the future, the main research work will focus on thermal conductivity measurement at low temperature region, which has extremely potential to prove the existence of majorana particles in the field of physics.
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Keywords: Topological insulators, Superconductivity, Electrochemical method, Crystal growth