Scanning tunneling microscopy study on symmetry breaking of charge density wave in FeGe

The complex symmetry breaking states in AV₃Sb₅ family have attracted extreme research attention, but controversy still exists, especially in the question of time reversal symmetry breaking of the charge density wave (CDW). Most recently, a chiral CDW has been suggested in kagome magnet FeGe, but the related study is very rare. Here, we use a scanning tunneling microscope to study the symmetry breaking behavior of both the short- and long-range CDWs in FeGe. Different from previous studies, our study reveals an isotropic long-range CDW without obvious symmetry breaking, while local rotational symmetry breaking appears in the short-range CDW, which may be related to the existence of strong structural disorders. Moreover, the charge distribution of the short-range CDW is inert to the applied external magnetic fields and the detailed spin arrangements of FeGe, inconsistent with the expectation of a chiral CDW associated with chiral flux. Our results rule out the existence of spontaneous chiral and rotational symmetry breaking in the CDW state of FeGe, putting strong constraints on the further understanding of CDW mechanism.