Quantum Interference Enhancement of the Spin-Dependent Thermoelectric Response

Runa X Bennett; Joshua R Hendrickson; Justin P Bergfield

doi:10.1021/acsnano.4c01297

Quantum Interference Enhancement of the Spin-Dependent Thermoelectric Response

ACS Nano. 2024 May 7;18(18):11876-11885. doi: 10.1021/acsnano.4c01297. Epub 2024 Apr 23.

Authors

Runa X Bennett¹, Joshua R Hendrickson², Justin P Bergfield^{1

3}

Affiliations

¹ Department of Physics, Illinois State University, Normal, Illinois 61790, United States.
² Air Force Research Laboratory, Sensors Directorate, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States.
³ Department of Chemistry, Illinois State University, Normal, Illinois 61790, United States.

Abstract

We investigate the influence of quantum interference (QI) and broken spin-symmetry on the thermoelectric response of node-possessing junctions, finding a dramatic enhancement of the spin-thermopower (S_s), figure-of-merit (Z_sT), and maximum thermodynamic efficiency (η_s^max) caused by destructive QI. Using many-body and single-particle methods, we calculate the response of 1,3-benzenedithiol and cross-conjugated molecule-based junctions subject to an applied magnetic field, finding nearly universal behavior over a range of junction parameters with S_s, Z_sT, and reaching peak values of $2 π / \sqrt{3} (k / e)$ , 1.51, and 28% of Carnot efficiency, respectively. We also find that the quantum-enhanced spin-response is spectrally broad, and the field required to achieve peak efficiency scales with temperature. The influence of off-resonant thermal channels (e.g., phonon heat transport) on this effect is also investigated.

Keywords: coherent transport; many-body transport theory; nonequilibrium Green’s functions; quantum interference; quantum spin-thermopower; single-molecule junction.