Anomalous transport properties of strained Sr₂RuO₄

Strain tuning Sr₂RuO₄ through the Lifshitz point, where the van Hove singularity of the electronic spectrum crosses the Fermi energy, causes a change in the temperature dependence of the resistivity [1]. This is rather surprising as usually a single, “hot” point on the Fermi surface does not influence the transport properties of a system. However there are exceptions to this rule [2]. In this talk we discuss a multi-band tight-binding model for strained Sr₂RuO₄ where the Fermi surface crosses the van Hove point. Following [2], we show that this van Hove singularity can cause a change in the temperature and frequency dependence of the conductivity of the system over a wide regime of temperatures and frequencies. For the resistivity the usual T² dependence becomes T²log(1/T), consistent with [1]. Interestingly, this behavior only extends down to lowest temperatures and frequencies if one includes all relevant bands that cross the Fermi energy. Put another way, the inclusion of additional “cold” states on the Fermi surface makes the anomalous temperature dependence more robust.

[1] M. E. Barber, A.S. Gibbs, Y. Maeno, A.P. Mackenzie, and C.W. Hicks, Phys. Rev. Lett. 120, 076602 (2018).

[2] C. H. Mousatov, E. Berg, and S. A. Hartnoll, Proc. Natl. Acad. Sci. 117, 2852 (2020).