Spectroscopic Evidence for an Additional Symmetry Breaking in the Nematic State of FeSe Superconductor

摘要

In iron-based superconductors,FeSe has the simplest crystal structure which consists solely of the basic building block,the FeSe layers,that dictates the superconductivity.It undergoes a structural phase transition at around 90 K to enter a nematic state but without a long-range magnetic order.So,FeSe is an ideal system to investigate the nematicity and superconducting mechanism in iron-based superconductors,It represents a unique system that superconductivity and nematicity coexist in the superconducting stale,giving rise to its distinct electronic structure and superconducting gap structure.