Quasiparticle properties of thin-film Sr₂RuO₄

Recent developments in the epitaxial growth of Sr₂RuO₄ have enabled the reproducible production of high quality superconducting films. These epitaxially-grown films provide a unique opportunity to the study of the effect of biaxial strain on Sr₂RuO₄, complementing the uniaxial strain studies on single-crystal, which shows a high sensitivity of T_c to strain. T_c in Sr₂RuO₄, however, is also extremely sensitive to disorder, and disentangling the combined effects of disorder and strain on T_c has proven difficult. We measure the Shubnikov-de Haas effect in Sr₂RuO₄ thin film grown on LSAT substrates, which corresponds to a strain state of 0.045% A_1g tensile strain. We are able to observe all three Fermi surfaces and extract their Fermi surface areas, cyclotron effective masses, and the quantum lifetimes of the quasiparticles. To understand the limiting factors of film quality, we model the magnetotransport and find that the quantum lifetime agrees well with the transport lifetime, indicating that large-angle point scattering is likely the limiting factor of the quasiparticle lifetime, rather than extended defects like substrate step edges or strain gradients.