Evidence for nematic superconductivity of topological surface states in PbTaSe2

Tian Le, Yue Sun, Hui-Ke Jin, Liqiang Che, Lichang Yin, Jie Li, G. M. Pang, C. Q. Xu, L. X. Zhao, S. Kittaka, T. Sakakibara, K. Machida, R. Sankar, H. Q. Yuan, G. F. Chen, Xiaofeng Xu, Shiyan Li, Yi Zhou, and Xin Lu

Jul 16, 2019

Received Date: 2nd July 19

Spontaneous symmetry breaking has been a paradigm to describe the phase transitions in condensed matter physics. In addition to the continuous electromagnetic gauge symmetry, an  unconventional superconductor can break discrete symmetries simultaneously, such as time reversal and lattice rotational symmetry. In this work we report a characteristic in-plane 2-fold behaviour of the resistive upper critical field and point-contact spectra on the superconducting semimetal PbTaSe2 with topological nodal-rings, despite its hexagonal lattice symmetry (or D3h in bulk while C3v on surface, to be precise). However, we do not observe any lattice rotational symmetry breaking signal from field-angle-dependent specific heat. It is worth noting that such surface-only electronic nematicity is in sharp contrast to the observation in the topological superconductor candidate, CuxBi2Se3, where the nematicity occurs in various bulk measurements. In combination with theory, superconducting nematicity is likely to emerge from the topological surface states of PbTaSe2, rather than the proximity effect. The issue of time reversal symmetry breaking is also addressed. Thus, our results on PbTaSe2 shed new light on possible routes to realize nematic superconductivity with nontrivial topology.

Read in full at arXiv.

This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.


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