Title: Growth of metallic delafossite $\mathrm{PdCo}{\mathrm{O}}_2$ by molecular beam epitaxy

Abstract

The Pd- and Pt-based ABO₂ delafossites are a novel class of layered, triangular oxides with two-dimensional electronic structure and a large conductivity that rivals the noble metals. In this work, we report successful growth of the metallic delafossite PdCoO₂ by molecular beam epitaxy (MBE). The key challenge is controlling the oxidation of Pd in the MBE environment where phase segregation is driven by the reduction of PdCoO₂ to cobalt oxide and metallic palladium. This is overcome by combining low-temperature (300 °C) atomic layer-by-layer MBE growth in the presence of reactive atomic oxygen with a postgrowth high-temperature anneal. Thickness dependence (5–265 nm) reveals that in the thin regime (<75 nm), the resistivity scales inversely with thickness, likely dominated by surface scattering; for thicker films, the resistivity approaches the values reported for the best bulk crystals at room temperature, but the low-temperature resistivity is limited by structural twins. Our report shows that the combination of MBE growth and a postgrowth anneal provides a route to creating high-quality films in this interesting family of layered, triangular oxides.

Authors:

Brahlek, Matthew  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2900-0648"

Rimal, Gaurab ^[2]; Ok, Jong Mok  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-5190-3117"

Mukherjee, Debangshu  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-0437-9807"

Mazza, Alessandro R.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-7206-1334"

Lu, Qiyang  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-9155-3684"

Lee, Ho Nyung  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-2180-3975"

Ward, T. Zac  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-1027-9186"

Unocic, Raymond R.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-1777-8228"

Eres, Gyula  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2690-5214"

Oh, Seongshik ^[2]

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Rutgers Univ., Piscataway, NJ (United States)

Publication Date:

Tue Sep 03 00:00:00 EDT 2019

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; USDOE

OSTI Identifier:

1561648

Alternate Identifier(s):

OSTI ID: 1560305

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Materials

Additional Journal Information:

Journal Volume: 3; Journal Issue: 9; Journal ID: ISSN 2475-9953

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Delafossite; PdCoO2; Triangular oxides; Thin films; Epitaxy