Investigation of the universal scattering rate in PdCrO₂ by high energy electron irradiation

PdCrO₂ is an extremely pure magnetic delafossite metal. It combines both possibilities for the motion of electrons in a solid: a nearly free electron metal and a Mott insulating state.
The resistivity of PdCrO₂ exhibits a T-linear dependence between 150 K and 300 K. In the region of the T-linear resistivity, the scattering rate per kelvin is well approximated by the ratio k_B/h. A number of other materials reveal similar results, in spite of large differences in the microscopic origins of the scattering [1].
To investigate the universal behaviour of the scattering rate, we conducted a study of the influence of point defects on the resistivity of PdCrO₂, the results of which we report here. We introduced point defects to FIB microstructures of PdCrO₂ by irradiating them with high-energy electrons. Comparing the results with those on PdCoO₂, we confirm that the increase in the resistivity is dominated by defects in Pd layers. Matthiessen's rule is obeyed in the T-linear region, indicating that the inelastic scattering events could be considered independent from the elastic ones.
[1] J. A. N. Bruin, Science Vol. 339, pp. 804-807