First-Order Phase Transition versus Spin-State Quantum-Critical Scenarios in Strain-Tuned Epitaxial Cobaltite Thin Films

Published

February 14, 2024

Author(s)

John Dewey, Vipul Chaturvedi, Tatiana Webb, Prachi Sharma, William Postiglione, P. Quarterman, Purnima Balakrishnan, Brian Kirby, Lucca Figari, Caroline Korostynski, Andrew Jacobson, Turan Birol, Rafael Fernandes, Abhay Pasupathy, Chris Leighton

Abstract

Pr-containing perovskite cobaltites exhibit unusual valence transitions, coupled to coincident structural, spin-state, and metal-insulator transitions. Heteroepitaxial strain was recently used to control these phenomena in the model (Pr1−yYy )1−xCaxCoO3−δ system, stabilizing a nonmagnetic insulating phase under compression (with a room-temperature valence/spin-state/metal-insulator transition) and a ferromagnetic (FM) metallic phase under tension, thus exposing a potential spin-state quantum-critical point. The latter has been proposed in cobaltites and can be probed in this system as a function of a disorder-free variable (strain). We study this here via thickness-dependent strain relaxation in compressive SrLaAlO4(001)/(Pr0.85Y0.15 )0.70Ca0.30CoO3−δ epitaxial thin films to quasicontinuously probe structural, electronic, and magnetic behaviors across the nonmagneticinsulator/FM-metal boundary. High-resolution x-ray diffraction, electronic transport, magnetometry, polarized neutron reflectometry, and temperature-dependent magnetic force microscopy provide a detailed picture, including abundant evidence of temperature- and strain-dependent phase coexistence. This indicates a first-order phase transition as opposed to spin-state quantum-critical behavior, which we discuss theoretically via a phenomenological Landau model for coupled spin-state and magnetic phase transitions.

Citation

Physical Review B

Volume

109

Issue

5

Pub Type

Journals

Download Paper

https://doi.org/10.1103/PhysRevB.109.054419

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Keywords

strain, valence transition, spin-state transition, metal-insulator transition, first-order phase transition, magnetism, complex oxides, thin films

Citation

Dewey, J. , Chaturvedi, V. , Webb, T. , Sharma, P. , Postiglione, W. , Quarterman, P. , Balakrishnan, P. , Kirby, B. , Figari, L. , Korostynski, C. , Jacobson, A. , Birol, T. , Fernandes, R. , Pasupathy, A. and Leighton, C. (2024), First-Order Phase Transition versus Spin-State Quantum-Critical Scenarios in Strain-Tuned Epitaxial Cobaltite Thin Films, Physical Review B, [online], https://doi.org/10.1103/PhysRevB.109.054419, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957341 (Accessed December 26, 2024)