Communications Physics (Feb 2025)

Absence of diode effect in chiral type-I superconductor NbGe2

  • Dong Li,
  • Zouyouwei Lu,
  • Wenxin Cheng,
  • Xiaofan Shi,
  • Lihong Hu,
  • Xiaoping Ma,
  • Yue Liu,
  • Yuki M. Itahashi,
  • Takashi Shitaokoshi,
  • Peiling Li,
  • Hua Zhang,
  • Ziyi Liu,
  • Fanming Qu,
  • Jie Shen,
  • Qihong Chen,
  • Kui Jin,
  • Jinguang Cheng,
  • Jens Hänisch,
  • Huaixin Yang,
  • Guangtong Liu,
  • Li Lu,
  • Xiaoli Dong,
  • Yoshihiro Iwasa,
  • Jiangping Hu

DOI
https://doi.org/10.1038/s42005-025-01960-2
Journal volume & issue
Vol. 8, no. 1
pp. 1 – 8

Abstract

Read online

Abstract Symmetry elegantly governs the fundamental properties and derived functionalities of condensed matter. For instance, realizing the superconducting diode effect (SDE) demands breaking space-inversion and time-reversal symmetries simultaneously. Although the SDE is widely observed in various platforms, its underlying mechanism remains debated, particularly regarding the role of vortices. Here, we systematically investigate the nonreciprocal transport in the chiral type-I superconductor NbGe2. Moreover, we induce type-II superconductivity with elevated superconducting critical temperature on the artificial surface by focused ion beam irradiation, enabling control over vortex dynamics in NbGe2 devices. Strikingly, we observe negligible diode efficiency (Q < 2%) at low magnetic fields, which rises significantly to Q ~ 50% at high magnetic fields, coinciding with an abrupt increase in vortex creep rate when the superconductivity of NbGe2 bulk is suppressed. These results unambiguously highlight the critical role of vortex dynamics in the SDE, in addition to the established symmetry rules.