Magneto-thermal conductivity effect and enhanced thermoelectric figure of merit in Ag2Te

Abstract

In this study, we report a large magneto-thermal conductivity effect, potentially usable in heat flow switches and thermoelectric devices, in Ag2Te over a wide temperature range, including room temperature. When a magnetic field of μ0 H = 9 T is applied to Ag2Te at 300 K along the direction perpendicular to the heat and electric currents, the thermal conductivity κ decreases by a remarkable 61%. This effect is mainly caused by the suppressed electronic thermal conductivity in association with a significant magnetoresistance effect, but the suppression of the thermal conductivity is larger than that of the electrical conductivity, presumably due to a field-induced decrease in the Lorenz ratio. Its very low lattice thermal conductivity, as low as 0.5 W m−1 K−1, also greatly contributes to the large relative magneto-thermal conductivity effect. The significant decrease in thermal conductivity and the 18% increase in the Seebeck coefficient S lead to a nearly 100% increase in the thermoelectric figure of merit zT = S2 σTκ−1 despite the 43% decrease in electrical conductivity σ.

Dilute but significant: low cation concentration affects field dependent properties of Eu2Ga11Sn35

“…To the best of our knowledge, only a few reports exist of magneto-suppressed k in semiconductors. [43][44][45] Furthermore, such phenomena have not been observed in any other clathrate material to date. Typically, the change in k e due to magnetoresistance results in magneto-suppressed k in semimetals and narrow-gap semiconductors.…”

“…Typically, the change in k e due to magnetoresistance results in magneto-suppressed k in semimetals and narrow-gap semiconductors. 44,46…”