Mona Zebarjadi1
University of Virginia1
The phase transition from crystal to crystal or crystal to amorphous is accompanied by electron and phonon dispersion changes and hence sharp modifications of electronic and phononic transport properties versus temperature. In particular, the strong variations of the Seebeck coefficient and the heat capacity with temperature can be used for the design of heat management devices. Sharp changes in the Seebeck coefficient result in significant Thomson coefficients (τ = TdS/dT, T is temperature). The Thomson effect induces heat release or absorption under the simultaneous application of a charge current and a temperature gradient in conductors, with applications in refrigeration. Thomson modules are not currently used. Their efficiency is barely studied as most materials show a minor Thomson coefficient much smaller than the Seebeck. Recently, Uchida's group reported a giant Thomson coefficient for FeRh alloys as a result of a phase transition. In this talk, I will present our results of phase transition-induced thermal hysteresis in FeRh alloys and 1T’-Td phase transition in type II Weyl semimetallic layered materials MoTe<sub>2</sub> and Mo<sub>1-x</sub>W<sub>x</sub>Te<sub>2</sub>. In the latter case, we show consistency between the Seebeck hysteresis and direct measurements of the crystallographic angle using temperature-dependent X-ray diffraction. I will discuss how the Thomson coefficient is related to other materials' properties and can be used for refrigeration.