Applying in-plane uniaxial pressure to strongly correlated low-dimensional systems has been shown to tune the electronic structure dramatically. For example, the unconventional superconductor Sr2RuO4 can be tuned through a single Van Hove singularity which results in a strong enhancement of both Tc and Hc2. Out-of-plane (c axis) uniaxial pressure is expected to tune the quasi-two-dimensional structure even more strongly, causing it to approach two Van Hove singularities simultaneously. Here we achieve a record value of 3.2 GPa compression along the c axis of Sr2RuO4. Although the rise in Hc2 shows that we are indeed approaching the van Hove points, Tc is suppressed, a result that contradicts expectations based on simple two-dimensional models. As a first attempt to take the third dimension into account, we present three-dimensional calculations in the weak interaction limit, and discuss the extent to which they are consistent with observation. Our experimental results highlight the importance of out-of-plane effects in low-dimensional systems in general and provide new constraints on theories of the pairing interaction in Sr2RuO4.
@article{arxiv.2111.06228,
title = {The Superconductivity of Sr$_2$RuO$_4$ Under $c$-Axis Uniaxial Stress},
author = {Fabian Jerzembeck and Henrik S. Røising and Alexander Steppke and Helge Rosner and Dmitry A. Sokolov and Naoki Kikugawa and Thomas Scaffidi and Steven H. Simon and Andrew P. Mackenzie and Clifford W. Hicks},
journal= {arXiv preprint arXiv:2111.06228},
year = {2022}
}