Pair density wave state in a monolayer high-Tc iron-based superconductor

Yanzhao Liu; Tianheng Wei; Guanyang He; Yi Zhang; Ziqiang Wang; Jian Wang

doi:10.1038/s41586-023-06072-x

Pair density wave state in a monolayer high-T_c iron-based superconductor

Nature. 2023 Jun;618(7967):934-939. doi: 10.1038/s41586-023-06072-x. Epub 2023 Jun 28.

Authors

Yanzhao Liu^#¹, Tianheng Wei^#¹, Guanyang He¹, Yi Zhang², Ziqiang Wang³, Jian Wang^{4

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Affiliations

¹ International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
² Department of Physics, Shanghai University, Shanghai, China.
³ Department of Physics, Boston College, Chestnut Hill, MA, USA. wangzi@bc.edu.
⁴ International Center for Quantum Materials, School of Physics, Peking University, Beijing, China. jianwangphysics@pku.edu.cn.
⁵ Collaborative Innovation Center of Quantum Matter, Beijing, China. jianwangphysics@pku.edu.cn.
⁶ Hefei National Laboratory, Hefei, China. jianwangphysics@pku.edu.cn.
⁷ CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, China. jianwangphysics@pku.edu.cn.
⁸ Beijing Academy of Quantum Information Sciences, Beijing, China. jianwangphysics@pku.edu.cn.

^# Contributed equally.

PMID: 37380693
DOI: 10.1038/s41586-023-06072-x

Abstract

The pair density wave (PDW) is an extraordinary superconducting state in which Cooper pairs carry non-zero momentum^1,2. Evidence for the existence of intrinsic PDW order in high-temperature (high-T_c) cuprate superconductors^3,4 and kagome superconductors⁵ has emerged recently. However, the PDW order in iron-based high-T_c superconductors has not been observed experimentally. Here, using scanning tunnelling microscopy and spectroscopy, we report the discovery of the PDW state in monolayer iron-based high-T_c Fe(Te,Se) films grown on SrTiO₃(001) substrates. The PDW state with a period of λ ≈ 3.6a_Fe (a_Fe is the distance between neighbouring Fe atoms) is observed at the domain walls by the spatial electronic modulations of the local density of states, the superconducting gap and the π-phase shift boundaries of the PDW around the vortices of the intertwined charge density wave order. The discovery of the PDW state in the monolayer Fe(Te,Se) film provides a low-dimensional platform to study the interplay between the correlated electronic states and unconventional Cooper pairing in high-T_c superconductors.