Acoustic-Soft Optical Mode Coupling Leads to Negative Thermal Expansion of GeTe near the Ferroelectric Phase Transition

Abstract

GeTe is a well-known ferroelectric and thermoelectric material that undergoes a structural phase transition from a rhombohedral to the rocksalt structure at $\sim 600-700$ K. We present a first principles approach to calculate the thermal expansion of GeTe in the rhombohedral phase up to the Curie temperature. We find the minimum of the Helmholtz free energy with respect to each structural parameter in a manner similar to the traditional Gr{ü}neisen theory, and account for the temperature dependence of elastic constants. We obtain the temperature variation of the structural parameters of rhombohedral GeTe in very good agreement with experiments. In particular, we correctly reproduce a negative volumetric thermal expansion of GeTe near the phase transition. We show that the negative thermal expansion is induced by the coupling between acoustic and soft transverse optical phonons, which is also responsible for the low lattice thermal conductivity of GeTe.

References in corpus (14)

• Separable Dual Space Gaussian Pseudo-potentials
• High-accuracy first-principles determination of the structural, vibrational and thermodynamical properties of diamond, graphite, and derivatives
• Systematic treatment of displacements, strains and electric fields in density-functional perturbation theory
• Giant Anharmonic Phonon Scattering in PbTe
• Second order structural phase transitions, free energy curvature, and temperature-dependent anharmonic phonons in the self-consistent harmonic approximation: theory and stochastic implementation
• Microscopic mechanism of low thermal conductivity in lead-telluride
• Intrinsic localized mode and low thermal conductivity of PbSe
• Phonon anharmonicity and negative thermal expansion in SnSe
• Ab Initio Phonon Dispersions for PbTe
• A nuclear quantum effect with pure anharmonicity and the anomalous thermal expansion of silicon
• Anomalous thermal conductivity and suppression of negative thermal expansion in ScF3
• Anomalous temperature-induced volume contraction in GeTe
• Broadband Phonon Scattering in PbTe-based Materials Driven Near the Ferroelectric Phase Transition by Strain or Alloying
• Anisotropic thermal expansion of bismuth from first principles

Cited by in corpus (5)

• Thermal Expansion in Insulating Solids From First Principles
• Anisotropic thermal expansion and thermomechanic properties of monolayer $\beta$-Te
• Effect of the polar distortion on the thermoelectric properties of GeTe
• Approximations in first-principles volumetric thermal expansion determination
• Non-thermal transport of energy driven by photoexcited carriers in switchable solid states of GeTe