Secondary Phase Limited Metal-Insulator Phase Transition in Chromium Nitride Thin Films

Bidesh Biswas; Sourjyadeep Chakraborty; Anjana Joseph; Shashidhara Acharya; Ashalatha Indiradevi Kamalasanan Pillai; Chandrabhas Narayana; Vijay Bhatia; Magnus Garbrecht; Bivas Saha

doi:10.1016/j.actamat.2022.117737

arXiv · 2201.07442

Secondary Phase Limited Metal-Insulator Phase Transition in Chromium Nitride Thin Films

Bidesh Biswas·Sourjyadeep Chakraborty·Anjana Joseph·Shashidhara Acharya·Ashalatha Indiradevi Kamalasanan Pillai·Chandrabhas Narayana·Vijay Bhatia·Magnus Garbrecht·Bivas Saha

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Abstract

Chromium nitride (CrN) is a well-known hard coating material that has found applications in abrasion and wear-resistant cutting tools, bearings, and tribology applications due to its high hardness, high-temperature stability, and corrosion-resistant properties. In recent years, CrN has also attracted significant interest due to its high thermoelectric power factor, and for its unique and intriguing metal-insulator phase transition. While CrN bulk single-crystals exhibit the characteristic metal-insulator transition accompanied with structural (orthorhombic-to-rocksalt) and magnetic (antiferromagnetic-to-paramagnetic) transition at ~260-280K, observation of such phase transition in thin-film CrN has been scarce and highly debated. In this work, the formation of the secondary metallic Cr2N phase during the growth is demonstrated to inhibit the observation of metal-insulator phase transition in CrN thin films. When the Cr-flux during deposition is reduced below a critical limit, epitaxial and stoichiometric CrN thin film is obtained that reproducibly exhibits the phase transition. Annealing of the mixed-phase film inside reducing NH3 environment converts the Cr2N into CrN, and a discontinuity in the electrical resistivity at ~ 277 K appears which supports the underlying hypothesis. A clear demonstration of the origin behind the controversy of the metal-insulator transition in CrN thin films marks significant progress and would enable its nanoscale device realization.

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Bidesh Biswas, Sourjyadeep Chakraborty, Anjana Joseph, Shashidhara Acharya, Ashalatha Indiradevi Kamalasanan Pillai, Chandrabhas Narayana, Vijay Bhatia, Magnus Garbrecht, Bivas Saha. 2022-01-19. Secondary Phase Limited Metal-Insulator Phase Transition in Chromium Nitride Thin Films. https://doi.org/10.1016/j.actamat.2022.117737

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