Brandi Wooten1,Ryo Iguchi2,Ken-ichi Uchida2,3,Gerrit Bauer3,4,Joseph Heremans1
The Ohio State University1,National Institute for Materials Science2,Tohoku University3,University of Groningen4
Brandi Wooten1,Ryo Iguchi2,Ken-ichi Uchida2,3,Gerrit Bauer3,4,Joseph Heremans1
The Ohio State University1,National Institute for Materials Science2,Tohoku University3,University of Groningen4
We present data on controlling the thermal conductivity and diffusivity of a bulk ferroelectric PZT material with an electric field. The results are consistent with a theory [1] stating that certain phonons carry a polarization current <i>j<sub>P</sub></i> as well as a heat current <i>j<sub>q</sub></i>, with a proportionality factor labeled the polarization Peltier coefficient P = -<i>j<sub>q</sub> / j<sub>p</sub></i>|<sub>¶</sub><i><sub>T</sub></i><sub>=0 </sub>. Hopkins and colleagues [2] reported that piezoelectric films have a thermal conductivity that decreases with external electric field due to an increase in ferroelectric domain wall density in thin films, which increases phonon scattering. We propose that in bulk ferroelectrics an external electric field alters the density of the polarization current-carrying phonons, by analogy with the effect of an external magnetic field on the magnon thermal conductivity in ferromagnets [3]. We quantify our results on the electric field dependent thermal conductivity and diffusivity, and on the temperature dependence of the electrical susceptibility, in terms of the single coefficient P. The values for P obtained from the three independent measurements agree to within a factor of two, which is surprisingly good given the elementary nature of the theory.<br/>[1] <i>Phys. Rev. Lett. </i><b>126</b>, 187603 (2021); [2] <i>Nano Lett</i>. <b>15</b>, 1791-1795 (2015); [3] <i>Phys. Rev. B</i> <b>91</b> 226401 (2015)<br/>Funding: NSF DMR 2011876; USD/R&E National Defense Education Program / BA-1 Basic Research - Science, Mathematics, and Research for Transformation (SMART) Scholarship (BLW)