Sub-THz momentum drag and violation of Matthiessen's rule in an ultraclean ferromagnetic SrRuO${}_3$ metallic thin film

Abstract

SrRuO${}_3$, a ferromagnet with an approximately 160\,K Curie temperature, exhibits a $T^2$ dependent dc resistivity below $\approx$ 30 K. Nevertheless, previous optical studies in the infrared and terahertz range show non-Drude dynamics at low temperatures which seem to contradict a Fermi-liquid picture with long-lived quasiparticles. In this work, we measure the low-frequency THz range response of thin films with residual resistivity ratios, ${\rho }_{300K}/{\rho }_{4K}\approx$ 74. Such low disorder samples allow an unprecedented look at the effects of electron-electron interactions on low-frequency transport. At temperatures below 30 K, we found both a very sharp zero-frequency mode which has a width narrower than $k_{B}T/\hslash$ as well as a broader zero frequency Lorentzian that has at least an order of magnitude larger scattering rate. Both features have temperature dependencies consistent with a Fermi-liquid with the wider feature explicitly showing a T${}^2$ scaling. Such two -Drude transport sheds light on previous reports of the violation of Mathielssen's rule and extreme sensitivity to disorder in metallic ruthenates. We consider a number of possibilities for the origin of the two feature optical conductivity including multiband effects that arise from momentum conserving interband scattering and the approximate conservation of a pseudo-momentum that arises from quasi-1D Fermi surfaces.

main text 5 pages, 3 figures

References in corpus (1)

• Quasiparticle Mass Enhancement and Temperature Dependence of the Electronic Structure of Ferromagnetic SrRuO3 Thin Films

Cited by in corpus (3)

• Materials challenges for SrRuO3: from conventional to quantum electronics
• Separated transport relaxation scales and interband scattering in SrRuO${}_3$, CaRuO${}_3$, and Sr${}_2$RuO${}_4$ thin films
• Low-temperature transport in high-conductivity correlated metals: a density-functional plus dynamical mean-field study of cubic perovskites