Paper
Magnetic-field induced momentum-dependent symmetry breaking in CsV$_3$Sb$_5$ revealed by magneto-ARPES
Authors
Jianwei Huang, Zheng Ren, Hengxin Tan, Jounghoon Hyun, Yichen Zhang, Thomas Hulse, Zhaoyu Liu, Jonathan M. DeStefano, Yaofeng Xie, Ziqin Yue, Junichiro Kono, Pengcheng Dai, Yu He, Aki Pulkkinen, Ján Minár, Jiun-Haw Chu, Ziqiang Wang, Binghai Yan, Rafael M. Fernandes, Ming Yi
Abstract
In quantum materials with multiple degrees of freedom with similar energy scales, intertwined electronic orders with distinct broken symmetries often appear in a strongly coupled fashion. Recently, in a class of kagome superconductors represented by CsVSb, experimental reports have suggested rotational symmetry breaking and time reversal symmetry breaking associated with a charge density wave (CDW) order, revealing an exotic nature of this CDW order. Here, utilizing our recently developed capability of performing angle-resolved photoemission spectroscopy in a tunable magnetic field (magneto-ARPES), we reveal momentum-selective response of the electronic structure of CsVSb to an external magnetic field. While the response in the electronic structure is clearly compatible with piezomagnetism, strong orbital-selectivity is observed. Specifically, bands associated with the vanadium -orbitals contributing to the Van Hove singularities (VHS) near the Brillouin zone (BZ) boundary exhibit selective spectral broadening that breaks C rotational symmetry and is odd in magnetic field, disappearing above the CDW transition. Meanwhile, the antimony -orbital dominated electron pocket at the BZ center becomes elongated under an applied field -- an effect that persists above the . Our observations delineate the origin of the time-reversal symmetry breaking associated with the vanadium VHS-bands at the onset of the CDW order, while the field-induced rotational symmetry breaking largely associated with the antimony orbitals reflects fluctuations beyond the CDW ordering temperature. Our magneto-ARPES work demonstrates a novel tuning knob for disentangling intertwined orders in the momentum space for quantum materials.