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 J Kirby; Hua Zhou; Huikai Cheng; Amanda Huon; Timothy Charlton; Michael R Fitzsimmons; Caroline Korostynski; Andrew Jacobson; Lucca Figari; Javier Garcia Barriocanal; Turan Birol; K Andre Mkhoyan; Chris Leighton

doi:10.1038/s41467-022-35024-8

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

Nat Commun. 2022 Dec 15;13(1):7774. doi: 10.1038/s41467-022-35024-8.

Authors

Vipul Chaturvedi¹, Supriya Ghosh¹, Dominique Gautreau^{1

2}, William M Postiglione¹, John E Dewey¹, Patrick Quarterman³, Purnima P Balakrishnan³, Brian J Kirby³, Hua Zhou⁴, Huikai Cheng⁵, Amanda Huon⁶, Timothy Charlton⁶, Michael R Fitzsimmons^{6

7}, Caroline Korostynski¹, Andrew Jacobson¹, Lucca Figari¹, Javier Garcia Barriocanal⁸, Turan Birol¹, K Andre Mkhoyan¹, Chris Leighton⁹

Affiliations

¹ Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA.
² School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
³ NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 60439, USA.
⁴ Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA.
⁵ Thermo Fisher Scientific, Hillsboro, OR, 97124, USA.
⁶ Neutron Scattering Division, Oak Ridge National Lab, Oak Ridge, TN, 37830, USA.
⁷ Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA.
⁸ Characterization Facility, University of Minnesota, Minneapolis, MN, 55455, USA.
⁹ Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA. leighton@umn.edu.

Abstract

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., 90 K in Pr_1-xCa_xCoO₃). Here, we show that in thin films of the complex perovskite (Pr_1-yY_y)_1-xCa_xCoO_3-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.

Abstract

Grants and funding