01.06.2021; Kolloquium
Manipulation of time-reversal-breaking superconductivity in Sr2RuO4 by uniaxial stress
Abstract:
Although the normal-state electronic structure of Sr2RuO4 is known with exceptional precision, even after two decades of research the symmetry of its certainly unconventional superconducting state is under strong debate, e.g. the long-favoured spin-triplet px ± ipy state is ruled out by recent NMR experiments [1]. However, in general time-reversal symmetry breaking (TRSB) superconductivity indicates complex two-component order parameters. Probing Sr2RuO4 under uniaxial stress offers the possibility to lift the degeneracy between such components [2]. One key prediction for Sr2RuO4, a splitting of the superconducting and TRSB transitions under uniaxial stress, has not been observed so far. I will show results of muon spin relaxation (μSR) measurements on Sr2RuO4 placed under uniaxial stress, wherein a large stress-induced splitting between the onset temperatures of superconductivity and TRSB was observed [3]. Moreover, at high stress beyond the van Hove singularity, a new spin-density-wave-ordered phase was detected for the first time. In order to perform μSR measurements under uniaxial stress, a custom piezoelectric-based pressure cell was developed [4]. This cell is going to be useful for a range of other materials in which the Fermi surface or magnetic interaction strengths can be tuned, leading to strong modifications of the electronic state.
[1] A. Pustogow, et al., Nature 574, 72 (2019); K. Ishida et al., J. Phys. Soc. Jpn. 89, 034712 (2020).
[2] C. Hicks, et al., Science 344, 283 (2014).
[3] V. Grinenko*, S. Ghosh* et al., Nature Physics, DOI: 10.1038/s41567-021-01182-7 (2021).
[4] S. Ghosh et al., Review of Scientific Instruments 91, 103902 (2020).
Host: H.-H. Klauß
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