Here we investigate epitaxial Hf0.5Zr0.5O2 ferroelectric thin films as potential candidates to be used as non-volatile electric-field-modulated thermal memories. The electric-field dependence of the thermal conductivity of metal/Hf0.5Zr0.5O2/Y2O3:ZrO2 devices is found to be hysteretic-resembling a polarization vs. electric field hysteresis loop-, reaching a maximum (minimum) at large applied positive (negative) electric fields from the top metallic electrode. This dynamic thermal response is compatible with the effects of the coupling between the ferroelectric polarization and oxygen ion migration in the Hf0.5Zr0.5O2 layer, in which the oxygen vacancies are the main phonon scattering centers and the polarization acts as an electrically active ion migration barrier that creates the hysteresis. This new mechanism enables two non-volatile states: high (ON) and low (OFF) thermal conductivity states when the electric field is removed, with an ON/OFF ratio of 1.6, which can be switched with applied voltages lower than -5 and +5 V, respectively. Both the ON and OFF states exhibit high stability over time, though the switching speed is limited by ion mobility in the Y2O3:ZrO2 electrode.
Barneo et al. (Mon,) studied this question.