Abstract

Topological superconductors have attracted wide-spreading interests for the bright application perspectives to quantum computing. Cu0.3Bi2Se3 is a rare bulk topological superconductor with an odd-parity wave function, but the details of the vector order parameter d and its pinning mechanism are still unclear. Here, we succeed in growing CuxBi2Se3 single crystals with unprecedented high doping levels. For samples with x  = 0.28, 0.36 and 0.37 with similar carrier density as evidenced by the Knight shift, the in-plane upper critical field Hc2 shows a two-fold symmetry. However, the angle at which the Hc2 becomes minimal is different by 90° among them, which indicates that the d-vector direction is different for each crystal likely due to a different local environment. The carrier density for x  = 0.46 and 0.54 increases substantially compared to x ≤ 0.37. Surprisingly, the in-plane Hc2 anisotropy disappears, indicating that the gap symmetry undergoes a transition from nematic to isotropic (possibly chiral) as carrier increases.

The understanding of the vector order parameter for Cu0.3Bi2Se3 topological superconductor remains unclear. Here, Kawai et al. report a surprising disappearance of the in-plane upper critical field anisotropy for CuxBi2Se3 single crystals with more carriers, indicating a transition from nematic to chiral superconducting gap symmetry.

Details

Title
Direction and symmetry transition of the vector order parameter in topological superconductors CuxBi2Se3
Author
Kawai, T 1 ; Wang, C G 2 ; Kandori, Y 1 ; Honoki, Y 1 ; Matano, K 1 ; Kambe, T 1 ; Guo-qing, Zheng 3   VIAFID ORCID Logo 

 Okayama University, Department of Physics, Okayama, Japan (GRID:grid.261356.5) (ISNI:0000 0001 1302 4472) 
 Institute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter Physics, Beijing, China (GRID:grid.458438.6) (ISNI:0000 0004 0605 6806) ; University of Chinese Academy of Sciences, School of Physical Sciences, Beijing, China (GRID:grid.410726.6) (ISNI:0000 0004 1797 8419) 
 Okayama University, Department of Physics, Okayama, Japan (GRID:grid.261356.5) (ISNI:0000 0001 1302 4472) ; Institute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter Physics, Beijing, China (GRID:grid.458438.6) (ISNI:0000 0004 0605 6806) 
Publication year
2020
Publication date
2020
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2343018054
Copyright
This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.