Expanded quantum vortex liquid regimes in the electron nematic superconductors FeSe1-xSx and FeSe1-xTex

M Čulo; S Licciardello; K Ishida; K Mukasa; J Ayres; J Buhot; Y-T Hsu; S Imajo; M W Qiu; M Saito; Y Uezono; T Otsuka; T Watanabe; K Kindo; T Shibauchi; S Kasahara; Y Matsuda; N E Hussey

doi:10.1038/s41467-023-39730-9

Expanded quantum vortex liquid regimes in the electron nematic superconductors FeSe_1-xS_x and FeSe_1-xTe_x

Nat Commun. 2023 Jul 12;14(1):4150. doi: 10.1038/s41467-023-39730-9.

Authors

M Čulo^#^{1

2}, S Licciardello^#³, K Ishida⁴, K Mukasa⁴, J Ayres⁵, J Buhot⁵, Y-T Hsu^{3

6}, S Imajo⁷, M W Qiu⁴, M Saito⁴, Y Uezono⁸, T Otsuka⁸, T Watanabe⁸, K Kindo⁷, T Shibauchi⁴, S Kasahara⁹, Y Matsuda¹⁰, N E Hussey^{11

12}

Affiliations

¹ High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands. mculo@ifs.hr.
² Institut za fiziku, Bijenička cesta 46, HR-10000, Zagreb, Croatia. mculo@ifs.hr.
³ High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands.
⁴ Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan.
⁵ H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK.
⁶ Center for Theory and Computation, National Tsing Hua University, No. 101, Section. 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan.
⁷ Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan.
⁸ Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan.
⁹ Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushimanaka, Kita-Ku, Okayama, 700-8530, Japan.
¹⁰ Department of Physics, Kyoto University, Sakyo-Ku, Kyoto, 606-8502, Japan.
¹¹ High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands. n.e.hussey@bristol.ac.uk.
¹² H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK. n.e.hussey@bristol.ac.uk.

^# Contributed equally.

Abstract

The quantum vortex liquid (QVL) is an intriguing state of type-II superconductors in which intense quantum fluctuations of the superconducting (SC) order parameter destroy the Abrikosov lattice even at very low temperatures. Such a state has only rarely been observed, however, and remains poorly understood. One of the key questions is the precise origin of such intense quantum fluctuations and the role of nearby non-SC phases or quantum critical points in amplifying these effects. Here we report a high-field magnetotransport study of FeSe_1-xS_x and FeSe_1-xTe_x which show a broad QVL regime both within and beyond their respective electron nematic phases. A clear correlation is found between the extent of the QVL and the strength of the superconductivity. This comparative study enables us to identify the essential elements that promote the QVL regime in unconventional superconductors and to demonstrate that the QVL regime itself is most extended wherever superconductivity is weakest.