Bidirectional Tuning of Thermal Conductivity in Ferroelectric Materials Using E-Controlled Hysteresis Characteristic Property
Chenhan Liu, Ping Lu, Zhongzhu Gu, Juekuan Yang, Yunfei Chen
Abstract
Unlike the wide range control of electrical conductivity, the tuning of thermal conductivity is difficult especially for the increase or bidirectional tuning. Traditional methods typically only decrease the thermal conductivity by increasing the phonon scattering. In this work, through first-principles calculations, the E-field-controlled hysteresis characteristic of ferroelectric materials is utilized to realize the bidirectional tuning of thermal conductivity. Under the electric field, the structure, i.e., the lattice constants and atomic coordinates, has an opposite response depending on the direction of the E-field, leading to the opposite change of thermal conductivity. Moreover, the electric field can also induce the domain wall response, i.e., the change of domain size or domain wall density, which can be combined with structure response to increase the range of bidirectional tuning. The tuning range for structure response has a weak dependence on temperature, while for domain wall response, it increases significantly with decreasing temperature since phonon transport at low temperature is sensitive to the domain wall scattering. The dimensionality effects (bulk, thin films, and nanowires) on the tuning range are also investigated. The calculation results show that bulk PTO and cross-plane direction of PTO thin film have a larger tuning range, while the in-plane directions of thin film and nanowire have a smaller value. The results in this work give a new guideline to search for bidirectional tuning of thermal conductivity.