Z3-vestigial nematic order due to superconducting fluctuations in the doped topological insulators NbxBi2Se3 and CuxBi2Se3

Chang-Woo Cho; Junying Shen; Jian Lyu; Omargeldi Atanov; Qianxue Chen; Seng Huat Lee; Yew San Hor; Dariusz Jakub Gawryluk; Ekaterina Pomjakushina; Marek Bartkowiak; Matthias Hecker; Jörg Schmalian; Rolf Lortz

doi:10.1038/s41467-020-16871-9

Z₃-vestigial nematic order due to superconducting fluctuations in the doped topological insulators Nb_xBi₂Se₃ and Cu_xBi₂Se₃

Nat Commun. 2020 Jun 16;11(1):3056. doi: 10.1038/s41467-020-16871-9.

Authors

Chang-Woo Cho^#¹, Junying Shen^#^{1

2}, Jian Lyu^{1

3}, Omargeldi Atanov¹, Qianxue Chen¹, Seng Huat Lee^{4

5}, Yew San Hor⁴, Dariusz Jakub Gawryluk⁶, Ekaterina Pomjakushina⁶, Marek Bartkowiak², Matthias Hecker⁷, Jörg Schmalian⁷, Rolf Lortz⁸

Affiliations

¹ Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
² Laboratory for Neutron and Muon Instrumentation, Paul Scherrer Institute, CH-5232, Villigen PSI, Switzerland.
³ Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China.
⁴ Department of Physics, Missouri University of Science and Technology, Rolla, MO, 65409, USA.
⁵ 2D Crystal Consortium, Materials Research Institute, Pennsylvania State University, University Park, PA, 16802, USA.
⁶ Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, CH-5232, Villigen, PSI, Switzerland.
⁷ Institute for Theory of Condensed Matter and Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, Karlsruhe, Germany.
⁸ Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. lortz@ust.hk.

^# Contributed equally.

Abstract

A state of matter with a multi-component order parameter can give rise to vestigial order. In the vestigial phase, the primary order is only partially melted, leaving a remaining symmetry breaking behind, an effect driven by strong classical or quantum fluctuations. Vestigial states due to primary spin and charge-density-wave order have been discussed in iron-based and cuprate materials. Here we present the observation of a partially melted superconductivity in which pairing fluctuations condense at a separate phase transition and form a nematic state with broken Z₃, i.e., three-state Potts-model symmetry. Thermal expansion, specific heat and magnetization measurements of the doped topological insulators Nb_xBi₂Se₃ and Cu_xBi₂Se₃ reveal that this symmetry breaking occurs at [Formula: see text] above [Formula: see text], along with an onset of superconducting fluctuations. Thus, before Cooper pairs establish long-range coherence at T_c, they fluctuate in a way that breaks the rotational invariance at T_nem and induces a crystalline distortion.

Abstract

Grants and funding