2023/09/29 by Asaba, T., Onishi, A., Kageyama, Y. +16
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2309.16985
The quest for fascinating quantum states arising from the interplay between correlation, frustration, and topology is at the forefront of condensed-matter physics. Recently discovered nonmagnetic kagome metals AV3Sb5 (A= K, Cs, Rb) with charge density wave (CDW) and superconducting instabilities may host such exotic states. Here we report that an odd electronic nematic state emerges above the CDW transition temperature (T\rm CDW=94 K) in CsV3Sb5. High-resolution torque measurements reveal a distinct twofold in-plane magnetic anisotropy that breaks the crystal rotational symmetry below T^*≈130 K. However, no relevant anomalies are detected in the elastoresistance data near T^*, which excludes the even-parity ferro-orbital nematicity often found in other superconductors. Moreover, in the temperature range between T\rm CDW and T^*, conical rotations of magnetic field yield a distinct first-order phase transition, indicative of time-reversal symmetry breaking. These results provide thermodynamic evidence for the emergence of an odd-parity nematic order, implying that an exotic loop-current state precedes the CDW in CsV3Sb5.