Low-voltage driven ferroelectric thermal switch

Active and precise control of thermal energy is critical for efficient waste-heat management. Ferroelectrics, which exhibit tunable thermal transport behavior in response to external stimuli, emerge as promising thermal switch candidates owing to their (1) controllability via polarization under electric fields, (2) high thermal switching ratios, and (3) solid-state-based heat conduction suitable for practical applications. Accurately evaluating the electric field (E)-dependent thermal conductivity (k) is essential. This study presents an experimental platform capable of simultaneously measuring thermal conductivity, electrostriction-induced pressure under constant volume, polarization, and electric current in ferroelectrics. Using this platform, a bulk single-crystal relaxor ferroelectric (PMN-30PT) is investigated at various operating temperatures. Following high-temperature, low-frequency poling, PMN-30PT exhibits a record-high ∼25 % modulation in thermal conductivity under a low electric field (2 kV/cm). At elevated temperatures, the thermal switching ratio diminishes, consistent with the reduced polarization of the material. Beyond thermal characterization, this study demonstrates active heat flow modulation, exhibiting a ∼4 % reduction in heat flux near the coercive field relative to the zero-field condition, consistent with its k–E behavior. This study is the first to assess and utilize the dynamically tunable thermal transport behavior of bulk ferroelectrics, paving the way for ferroelectric-based thermal management technologies.