Giant electric-field induced thermal switching controlled by phonon scattering in a relaxor ferroelectric

The demand for high energy efficiency drives intense interest in thermal management technology. The active control of heat flow in materials can dramatically enhance device efficiency. Phonons are a major contributor to heat transfer in solids and controlling them through external stimuli is a key challenge for thermal management. However, altering phonons is difficult due to their weak and complicated interactions with applied fields. Here, we report significant changes in phonon transport with the application of an electric field in a commercial relaxor-based ferroelectric using neutron scattering and transport measurements. Phonon linewidths sharpen in the direction of the applied poling field and this results in a tripling of the thermal conductivity in that direction. We also observe a suppression of nanoscale antiferroelectric fluctuations along the poling direction and argue that this sharpens the phonons. This work highlights the potential of relaxor ferroelectrics for realizing solid-state heat switching, offering a promising avenue towards high-efficiency thermal management.