Abstract

Ultra-pure delafossite metals can present bulk mean free paths as long as tens of microns,
long enough such that the momentum conservation of the electron fluid might play a role in
electrical transport. As the signatures of this are most prominent in the mesoscopic limit, we
use focussed ion beam (FIB) techniques to thin down bulk samples, down to widths as small
as submicron, much smaller than the bulk mean free path. In this talk I will present
magnetotransport measurements in these highly-conducting delafossites at the mesoscopic
limit. Magnetic field introduces a variable length-scale, the cyclotron radius, in the system
which can be used to tune through different transport regimes. I will discuss the ballistic and
hydrodynamic signatures in the transport that becomes accessible through magnetic field
tuning in the mesoscopic samples of the non-magnetic delafossites PdCoO2 and PtCoO2.