Bound on Thermoelectric Power in a Magnetic Field within Linear Response

TL;DR

This paper establishes a universal bound on thermoelectric power in magnetic fields, showing power vanishes linearly near maximum efficiency and ruling out finite-power Carnot efficiency.

Contribution

It provides the first numerical evidence for a universal bound on thermoelectric power related to magnetic asymmetry in Onsager coefficients.

Findings

Power vanishes linearly as maximum efficiency is approached

Carnot efficiency cannot be achieved at finite power

Universal bound depends on magnetic-field induced asymmetry

Abstract

For thermoelectric power generation in a multi-terminal geometry, strong numerical evidence for a universal bound as a function of the magnetic-field induced asymmetry of the non-diagonal Onsager coefficients is presented. This bound implies, inter alia, that the power vanishes at least linearly when the maximal efficiency is approached. In particular, this result rules out that Carnot efficiency can be reached at finite power, which an analysis based on the second law only, would, in principle, allow.