Conduction electrons drive giant, nonlinear elastic response in Sr2RuO4

The flowing electrons and the lattice know about each other, and if the lattice changes for some reason there will be effects on the current patterns. If the flowing electrons interact strongly with each other, they can spontaneously change current patterns, but if that happens, the effect on the lattice is usually very weak. Indeed, because the lattice bonding is usually so strong, the lattice is often thought of as dominating the current-carrying electrons, and even a very weak change of the lattice is often proposed to be the driver of the current pattern change.

In newly published work, a team from our Institute has uncovered clear proof of a case in which a tiny fraction of the current-carrying electrons can dominate all the others and make the lattice much softer. After the experiment was performed in-house, we collaborated with colleagues from Germany, Japan, Korea and the United States to understand the surprising result. An explicit model constructed by the groups of Joerg Schmalian and Markus Garst at the Karlsruhe Institute of Technology was crucial to unravelling the detective story, as were results from complementary experiments published in 2022. The work gives a new perspective on a decades-old problem, and will, we hope, be influential for future research.