Magnetotransport properties in epitaxial films of metallic delafossite PdCoO2: Effects of thickness and width variations in Hall bar devices

Document Type

Article

Publication Date

5-1-2025

Abstract

We report on a combined structural and magnetotransport study of Hall bar devices of various lateral dimensions patterned side-by-side on epitaxial PdCoO2 thin films. We study the effects of both the thickness of the PdCoO2 film and the width of the channel on the electronic transport and the magnetoresistance properties of the Hall bar devices. All the films with thicknesses down to 4.88 nm are epitaxially oriented, phase-pure, and exhibit metallic behavior. At room temperature, resistivity values as low as 6.85 and 8.17μωcm are achieved in Hall bar devices with channel width W=2.5μm and W=10μm, respectively. For the 4.88 nm thick sample, we find that while the density of the conduction electrons is comparable in both channels, the electrons move about twice as fast in the narrower channel. At low temperatures, for Hall bar devices of channel width 2.5μm fabricated on epitaxial films of thicknesses 4.88 and 5.21 nm, the electron mobilities of ≈65 and 40cm2V-1s-1, respectively, are extracted. For thin-film Hall bar devices of width 10μm fabricated on the same 4.88 and 5.21 nm thick samples, the mobility values of ≈32 and 18cm2V-1s-1 are obtained. The magnetoresistance characteristics of these PdCoO2 films are observed to be temperature- dependent and exhibit a dependency with the orientation of the applied magnetic field. When the applied field is oriented 90° away from the crystal c-axis, a persistent negative MR at all temperatures is observed. However when the field is parallel to the c-axis, the negative magnetoresistance is suppressed at temperatures above 150 K.

Publication Source (Journal or Book title)

Physical Review Materials

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