Abstract
A nematic topological superconductor has an order parameter symmetry, which spontaneously breaks the crystalline symmetry in its superconducting state. This state can be observed, for example, by thermodynamic or upper critical field experiments in which a magnetic field is rotated with respect to the crystalline axes. The corresponding physical quantity then directly reflects the symmetry of the order parameter. We present a study on the superconducting upper critical field of the Nb-doped topological insulator NbxBi2Se3 for various magnetic field orientations parallel and perpendicular to the basal plane of the Bi2Se3 layers. The data were obtained by two complementary experimental techniques, magnetoresistance and DC magnetization, on three different single crystalline samples of the same batch. Both methods and all samples show with perfect agreement that the in-plane upper critical fields clearly demonstrate a two-fold symmetry that breaks the three-fold crystal symmetry. The two-fold symmetry is also found in the absolute value of the magnetization of the initial zero-field-cooled branch of the hysteresis loop and in the value of the thermodynamic contribution above the irreversibility field, but also in the irreversible properties such as the value of the characteristic irreversibility field and in the width of the hysteresis loop. This provides strong experimental evidence that Nb-doped Bi2Se3 is a nematic topological superconductor similar to the Cu- and Sr-doped Bi2Se3.
Recommended Citation
J. Shen et al., "Nematic Topological Superconducting Phase in Nb-Doped Bi₂Se₃," npj Quantum Materials, vol. 2, no. 1, Nature Publishing Group, Dec 2017.
The definitive version is available at https://doi.org/10.1038/s41535-017-0064-1
Department(s)
Physics
Keywords and Phrases
Superconducting Properties and Materials; Topological Matter
International Standard Serial Number (ISSN)
2397-4648
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2017 The Author(s), All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 4.0 License.
Publication Date
01 Dec 2017
Comments
Y.S.H. acknowledges support from National Science Foundation DMR-1255607.