Non-local electrodynamics in ReO3

The metallic oxide ReO3 is known for its remarkably low residual resistivity, being the most highly conducting of all oxide materials[1]. Such resistivity endows ReO3 with an extremely long low-temperature electronic mean free path (MFP), comparable to the ultrapure delafossites. Recent microwave spectroscopy measurements of one such delafossite—PdCoO2—have revealed a directional anomalous skin effect response that depends on the orientation of its hexagonally-faceted Fermi surface[2]. As with the conventional anomalous skin effect, this response indicates that ballistic (non-local) transport effects are dominant. Recent models for the anomalous skin effect response also predict anisotropic responses in materials with cubic Fermi surface facets[3]. ReO3 is an ideal candidate material for investigating this phenomenology as some of its Fermi surfaces have cubic facets. Here we present microwave spectroscopy measurements of high-purity ReO3 at low temperatures. We compare these results to conventional skin effect responses and discuss how a faceted Fermi surface might contribute to novel behaviours in high-purity metals.

[1] Falke et al., PRB 103, 115125 (2021)

[2] Baker et al., arXiv:2204.14239 (2022)

[3] Valentinis et al., arXiv:2204.13344 (2022)