Thermomechanical Stabilization of Electron Small Polarons in SrTiO₃ Assessed by the Quasiharmonic Approximation
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PhysRevB.95.161110.pdf
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Author(s)
Youssef, Mostafa Youssef Mahmoud
Yildiz, Bilge
Van Vliet, Krystyn J
Date Issued
April 2017
Journal
Physical Review B
Publisher
American Physical Society
Citation
Youssef, Mostafa; Yildiz, Bilge and Van Vliet, Krystyn J. "Thermomechanical Stabilization of Electron Small Polarons in SrTiO₃ Assessed by the Quasiharmonic Approximation." Physical Review B 95, no. 161110(R) (April 2017): 1-6. © 2017 American Physical Society
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Final published version
Abstract
We predict a predominance diagram for electron defects in the temperature-hydrostatic stress space for SrTiO₃ by combining density functional theory and the quasiharmonic approximation. We discovered two regimes where small polarons dominate: under tensile stress at lower temperature due to a larger relaxation volume of the defect Ω, and under compressive stress at higher temperature due to a smaller Ω and larger formation entropy. This provides a means to modulate the electronic conductivity via controlling the underlying charge carrier. Furthermore, the results challenge the common association between larger Ω and charge localization by demonstrating that at high temperature the free electron can induce larger Ω compared to the small polaron. This finding is attributed to the ability of the free electron to generate greater vibrational entropy upon finite isothermal expansion.
MIT Department
Massachusetts Institute of Technology. Department of Biological Engineering
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.95.161110
