报告题目：Impurity effect on spontaneous magnetic fields in Sr2RuO4
报 告 人：Prof. Vadim Grinenko, Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University
报告时间：2026年4月7日 10：00
报告地点：物理楼W105会议室
内容摘要：The nature of the broken time reversal symmetry (BTRS) state in Sr2RuO4 remains a long-standing puzzle, and its relation to superconductivity remains controversial. There are various universal predictions for the BTRS state when it is associated with a multicomponent superconducting order parameter [1]. In particular, in the BTRS superconducting state, spontaneous fields appear around crystalline defects, impurities, superconducting domain walls and sample surfaces. Here, we aimed to verify these predictions for Sr2RuO4 by performing muon spin relaxation (μSR) measurements on Sr2−xLaxRuO4 single crystals [2]. We observed that the enhanced muon spin depolarisation rate in the superconducting state ∆Λ, monotonically decreases with La doping. The observed behaviour is consistent with ∆Λ ∝ Tc2, indicating that homogeneous La substitution is not a source of spontaneous magnetic fields, but the spontaneous fields are altered by the suppression of superconducting critical temperature (Tc) with La-doping. Qualitatively different behaviour is observed for the effects of disorder and Ru inclusions. By analysing a large number of samples measured in the previous works, we found that the ∆Λ is small for pure Sr2RuO4 single crystals and increases with disorder or impurities. The strongest enhancement is observed in the crystals with Ru-inclusions, which show enhanced Tc. The comparative study allowed us to conclude that spontaneous fields in the BTRS superconducting state of Sr2RuO4 appear around inhomogeneities and, at the same time, decrease with the suppression of Tc. The observed behaviour is consistent with the prediction for multicomponent BTRS superconductivity.
[1] Y. Maeno, A. Ikeda, G. Mattoni, Nature Physics 20 (11), 1712-1718 (2024).
[2] Y. Li et al., arXiv:2512.24585.
报告人简介：Vadim Grinenko graduated from the National Research Nuclear University (MEPhI), Moscow, in 2004. He got a PhD in the National Research Center "Kurchatov Institute", Moscow, in 2008. After his PhD, he moved to Germany and joined the Institute for Metallic Materials in IFW Dresden, Germany, as a postdoc. At the end of 2015, Vadim moved to TU Dresden, Germany, as a PI. In 2015 and 2016, he was a visiting Associate Professor at Nagoya University. In 2022, Vadim moved to the TD Lee Institute in Shanghai. Now, he is a Tenured Fellow at TD Lee Institute and a Tenured Associate Professor at Shanghai Jiao Tong University. He works in the field of superconductivity and magnetism and has more than 70 publications.
