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Room-temperature valence transition in a strain-tuned perovskite oxide



Vipul Chaturvedi, Supriya Ghosh, Dominique Gautreau, William M. Postiglione, John E. Dewey, Patrick Quarterman, Purnima P. Balakrishnan, Brian Kirby, Hua Zhou, Huikui Cheng, Amanda Huon, Timothy Charlton, Michael R. Fitzsimmons, Caroline Korostynski, Andrew Jacobson, Lucca Figari, Javier Garcia Barriocanal, T. Birol, K. A. Mkhoyan, Chris Leighton


Cobalt oxides have long been understood to display intriguing phenomena known as spin-state crossovers, where the cobalt ion spin changes vs. temperature, pressure, etc. A very different situation was recently uncovered in praseodymium-containing cobalt oxides, where a first-order coupled spin-state/structural/metal-insulator transition occurs, driven by a remarkable praseodymium valence transition. Such valence transitions, particularly when triggering spin-state and metal-insulator transitions, offer highly appealing functionality, but have thus far been confined to cryogenic temperatures in bulk materials (e.g., 90K in Pr1-xCaxCoO3). Here, we show that in thin films of the complex perovskite (Pr1-yYy)1-xCaxCoO3-δ, heteroepitaxial strain tuning enables stabilization of valence-driven spin-state/structural/metal-insulator transitions to at least 291 K, i.e., around room temperature. The technological implications of this result are accompanied by fundamental prospects, as complete strain control of the electronic ground state is demonstrated, from ferromagnetic metal under tension to nonmagnetic insulator under compression, thereby exposing a potential novel quantum critical point.
Nature Communications


complex oxides, perovskites, strain, valence transition, metal insulator transition, magnetic thin films, spin-state transition, first-order transition, ferromagnetism


Chaturvedi, V. , Ghosh, S. , Gautreau, D. , Postiglione, W. , Dewey, J. , Quarterman, P. , Balakrishnan, P. , Kirby, B. , Zhou, H. , Cheng, H. , Huon, A. , Charlton, T. , Fitzsimmons, M. , Korostynski, C. , Jacobson, A. , Figari, L. , Garcia Barriocanal, J. , Birol, T. , Mkhoyan, K. and Leighton, C. (2022), Room-temperature valence transition in a strain-tuned perovskite oxide, Nature Communications, [online],, (Accessed May 29, 2024)


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Created December 15, 2022, Updated March 11, 2024