Bad Metal Behavior in SrRuO3

SrRuO3 resistance versus temperature

Terahertz measurements on SRO

A new class of materials known as so-called "bad metals" show transport  properties not understandable using conventional transport theory.  Their resistivities at high temperatures imply electron mean free paths less  than an inter-atomic distance, and their infrared conductivity is not in agreement with conventional Drude theory.  We are using SrRuO3 as a model system to study this phenomenon.

DC conductivity measurements on SrRuO3 films reveal some anomalous  behavior.  The resistance at high temperatures continues to rise linearly  with temperature beyond the point where conventional theories are no longer applicable Measurements of the frequency dependent conductivity by infrared reflectivity and terahertz time-domain spectroscopy, show an analytic structure fundamentally different from that predicted by the standard theory of metals. The low temperature resistance incrased like T2, as expected from electron-electron scattering.  Residual resistivities achieved are comparable to the best single crystal values.

Quantum oscillations in SRO

Resistivity change upon irradiation

Introducing disorder by means of electron irradiation also has an unusual effect, violating Matthiessen's rule. We observe quantum oscillations in the electrical resistivity verses field of a high-quality thin film of SrRuO3.  Our study demonstrates the existence of long-lived fermion quasiparticles at low temperatures, and strongly suggests that the ground state of SrRuO 3 is a Fermi liquid, even though conductivity measurements at higher temperatures show anomalous metallic behavior.


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