Symmetry Origins of the Field-Free Superconducting Diode Effect in the Kagome Superconductor CsV$_3$Sb$_5$

Xin-Jie Liu; Shengbiao Sun; Ke-Fan Song; Jia-Peng Peng; Xilin Feng; Lang Xiao; Tong Liu; Qilin Han; Ya-Qing Bie; Ning Kang; Xiaosong Wu; Yanfei Wu; Shouguo Wang; Kam Tuen Law; Shuo Wang; Dapeng Yu; Ben-Chuan Lin

arXiv · 2608.26022

Symmetry Origins of the Field-Free Superconducting Diode Effect in the Kagome Superconductor CsV$_3$Sb$_5$

Xin-Jie Liu·Shengbiao Sun·Ke-Fan Song·Jia-Peng Peng·Xilin Feng·Lang Xiao·Tong Liu·Qilin Han·Ya-Qing Bie·Ning Kang·Xiaosong Wu·Yanfei Wu·Shouguo Wang·Kam Tuen Law·Shuo Wang·Dapeng Yu·Ben-Chuan Lin

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Abstract

Field-free superconducting diode effects require both inversion-symmetry breaking and an internal time-reversal-symmetry (TRS) breaking field, making them sensitive probes of hidden order in superconductors. In centrosymmetric kagome AV$_3$Sb$_5$, the inversion symmetry generally should generally preclude the observation of the superconducting diode effect. Furthermore, though TRS breaking has been reported in the superconducting regime of CsV$_3$Sb$_5$, whether it is generated by superconductivity or inherited from charge-density-wave (CDW) order remains unresolved. Here we show that pristine CsV$_3$Sb$_5$ devices exhibit no intrinsic field-free superconducting diode effect, whereas surface oxidation or asymmetric etching activates a large nonreciprocal supercurrent. Moreover, the response is stochastic, with sweep-dependent polarity and magnitude, indicating metastable TRS-breaking domain configurations. Small out-of-plane magnetic fields stabilize the superconducting diode response, consistent with field selection of such domains. Finally, when long-range CDW order is suppressed by Ti doping, the SDE disappears. Our results establish the symmetry requirements for the field-free SDE in CsV$_3$Sb$_5$, reveal its stochastic domain-controlled character, and link superconducting-state TRS breaking to CDW-related order.

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Xin-Jie Liu, Shengbiao Sun, Ke-Fan Song, Jia-Peng Peng, Xilin Feng, Lang Xiao, Tong Liu, Qilin Han, Ya-Qing Bie, Ning Kang, Xiaosong Wu, Yanfei Wu, Shouguo Wang, Kam Tuen Law, Shuo Wang, Dapeng Yu, Ben-Chuan Lin. 2026-08-26. Symmetry Origins of the Field-Free Superconducting Diode Effect in the Kagome Superconductor CsV$_3$Sb$_5$. https://arxiv.org/abs/2608.26022

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