Low Temperature Thermoelectricity and Magnetism in Binary Metal Chalcogenides

Abstract

Though the development of efficient low temperature thermoelectric (TE) materials would signal a revolution in refrigeration technologies, little progress towards this has been made in the last half century. This stagnation, due largely to the competing electrical and thermal transport effects that govern TE performance, necessitates the development of novel road maps to predicting and synthesizing materials suitable for low temperature applications. To this end, here it is hypothesized that probing the relationship between magnetism and electrical and thermal transport properties may provide insight into developing such road maps that supplements conventional thermoelectric considerations. TE transport quantification of thermopower, resistivity, and carrier concentration is performed in conjunction with magnetic susceptibility measurements for antiferromagnetic binary metal chalcogenides Cr\(_{2}\)Se\(_{3}\) and MnTe\(_{2}\). The effect of dilute magnetic impurities on physical properties is also explored for Mn\(_{1-x}\)M\(_{x}\)Te\(_{2}\) (M=Cr and Fe, x=0.10; M=Co, x=0.05). It is observed that physical phenomena manifest side by side in both resistivity and susceptibility data, suggesting a correlation between electrical transport and magnetism. Electron-phonon, electron-electron, and electron-magnon interactions are discussed as possible explanations for abnormal Seebeck coefficient behavior, but more definitive conclusions require additional in depth quantitative approaches. Previously unpublished magnetic transitions in Cre\(_{2}\)Se\(_{3}\) and MnTe\(_{2}\) are also reported here for the first time.