Thermoelectric Properties of CrI3 Monolayer

Abstract

The promising thermoelectric properties of two-dimensional (2D) materials, owing to their appropriate combination of electrical and thermal transport properties has broaden their application in thermoelectric devices. Recently, the successful exfoliation of monolayer chromium tri-iodide CrI3, having robust intrinsic magnetism, has motivated us to investigate its thermoelectric properties in ferromagnetic (FM) and anti-ferromagnetic (AFM) states. Using density functional theory in addition with Boltzmann transport theory, we have calculated the band-structure, density of states, electrical and thermal conductivities, Seebeck coefficient and power factor for monolayer CrI3 in FM and AFM states. We show that in both magnetic states, CrI3 has an electrical conductivity $(\sigma /\tau \approx 10^{19}\, \Omega^{-1}m^{-1}s^{-1})$ comparable to graphene. For both magnetic states, no variation is observed in electrical and thermal conductivity for temperature less than 500 K. However, both conductivities is observed to increase significantly with further increase in temperature till 800 K. Interestingly, both conductivities in FM state are 10 times higher than AFM state, while the power factor for FM state is higher over AFM state, and hence indicates a good thermoelectric performance in FM state of CrI3 monolayer.