The Stress-Induced Lifshitz Transition in Sr2RuO4

Speaker: Dr Clifford Hicks -- Reader in Condensed Matter Physics, Birmingham / Group leader, Max Planck Dresden (CPFS)

Title: The Stress-Induced Lifshitz Transition in Sr2RuO4

Abstract: Sr2RuO4 is an unconventional superconductor and a moderately correlated metal. Under a uniaxial stress of 0.75 GPa applied along a <100> lattice direction, its largest Fermi surface undergoes a Lifshitz transition, from an electron-like to an open geometry. In this seminar, I will show stress-strain data that reveal that the low-temperature Young's modulus of Sr2RuO4 drops by about 10% in the vicinity of this transition, and then increases sharply on the other side. These anomalies in the Young's modulus are caused by changes in the integrated band energy of the occupied states. I will also show Hall effect data under uniaxial stress, that can be explained with a Hund's metal model of the normal state of Sr2RuO4. In a Hund's metal, interorbital scattering is suppressed, and electron-electron scattering occurs primarily within each orbital.