Thermoelectric effects in tunneling of spin-polarized electrons in a molecular transistor

TL;DR

This paper investigates thermoelectric effects in a spin-polarized molecular transistor under a temperature gradient, revealing negative differential thermoconductance and enhanced thermopower features influenced by vibronic effects, Coulomb interaction, and magnetic fields.

Contribution

It introduces a detailed analysis of thermoelectric properties in spin-polarized molecular transistors considering vibronic and Coulomb effects, highlighting optimal conditions for high thermoelectric efficiency.

Findings

Negative differential thermoconductance due to vibronic effects.

Multiple sign changes in thermopower with detuning energy.

Optimal parameters for maximum thermoelectric power identified.

Abstract

Thermal transmission in a molecular transistor with fully spin-polarized electrodes subjected to a temperature gradient is considered. The problem has been solved by using density matrix method in perturbation approach over small tunneling width. It has been found that due to the vibronic effects spintronic molecular transistor is characterized by negative differential thermoconductance. It has been demonstrated that in the dependence of thermopower $S$ on the detuning energy there is an increased number of points of change of the sign and magnitude of $S$ comparing with that of conventional molecular transistor. Optimal parameters, that provide the highest thermoelectric power at maximum efficiency $P_{me}$ for spintronic molecular transistor, have been found. The dependences of the figure of merit $ZT$ and $P_{me}$ on temperature and an external magnetic field have been calculated and the influence of Coulomb interaction on the thermolelectric properties has been studied. It has been revealed, that for non-zero Coulomb interaction more handy regime of thermoelectric device develops, characterized by continuous region of external magnetic fields, which provide high values of thermoelectric power.