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

Arnaud P. Nono Tchiomo (Louisiana State University) ; Anand Sharma (Louisiana State University) ; Sethulakshmi Sajeev (Louisiana State University) ; Anna Scheid (Max Planck Institute for Solid State Research) ; Peter A. van Aken (Max Planck Institute for Solid State Research) ; Takayuki Harada SAMURAI ORCID (Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science) ; Prosper Ngabonziza (Louisiana State University)

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Arnaud P. Nono Tchiomo, Anand Sharma, Sethulakshmi Sajeev, Anna Scheid, Peter A. van Aken, Takayuki Harada, Prosper Ngabonziza. Magnetotransport properties in epitaxial films of metallic delafossite PdCoO2: Effects of thickness and width variations in Hall bar devices. PHYSICAL REVIEW MATERIALS. 2025, 9 (5), . https://doi.org/10.1103/PhysRevMaterials.9.055001

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(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 8.17µ⁢Ωcm 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 40cm2⁢V−1⁢s−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 18cm2⁢V−1⁢s−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.

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Keyword: low dimensional materials, magnetotransport, thin films, oxides

Date published: 2025-05-22

Publisher: American Physical Society (APS)

Journal:

  • PHYSICAL REVIEW MATERIALS (ISSN: 24759953) vol. 9 issue. 5

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Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5535

First published URL: https://doi.org/10.1103/PhysRevMaterials.9.055001

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Updated at: 2025-06-17 16:30:28 +0900

Published on MDR: 2025-06-17 16:22:46 +0900

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