Predictive Control of Lattice Viscosity by Electric Fields in Displacive Ferroelectrics

Abstract Lattice viscosity quantifies the irreversible relaxation of momentum and stress mediated by phonon dynamics and provides a sensitive probe of anharmonicity and dissipation in crystalline solids. In ferroelectric and quantum-paraelectric materials, soft polar phonon modes dominate this response and are strongly coupled to external electric fields. Here we develop a microscopic theory of electric-field-dependent lattice viscosity based on linear response and phonon Green’s functions, explicitly incorporating anharmonic phonon–phonon interactions and nonlinear polarization effects. We show that, at temperatures above the ferroelectric transition, electric fields generically induce quadratic renormalization of phonon linewidths and frequencies , leading to a universal field dependence of the lattice viscosity governed by a small set of effective coefficients. We validate these predictions using first-principles density functional perturbation theory (DFPT) calculations implemented in Quantum ESPRESSO for representative systems, including the quantum paraelectric SrTiO₃ and the displacive ferroelectric BaTiO₃. The computed phonon dispersions, anharmonic linewidths, and inelastic scattering cross sections confirm the predicted quadratic field scaling, demonstrate strong mode selectivity associated with soft polar modes, and establish the microscopic origin of the dominant viscosity contributions. Based on these results, we establish a predictive model for the lattice viscosity Λ(E,T) that maps first-principles phonon properties directly to the electric-field and temperature dependence of lattice viscosity. Our findings reveal electric field as an effective and reversible control parameter for lattice dissipation, providing a predictive framework for electric-field control of dissipation in functional and quantum materials. We discuss implications for ferroelectric quantum criticality, phonon-mediated superconductivity, and field-tunable dissipation in oxide heterostructures and quantum devices, positioning lattice viscosity as a controllable transport property in quantum and functional materials.