Efficiency at Maximum Power of a Quantum Dot Heat Engine in an External Magnetic Field

We investigate the efficiency at maximum power of a nanothermoelectric heat engine consisting of one spin-degenerate quantum dot embedded between two reservoirs at different temperatures and chemical potentials in an external magnetic field. Based on the stochastic master equation the maximum power and the corresponding efficiency at maximum power are calculated in different external magnetic fields. The result shows that both the maximum power and the corresponding efficiency at maximum power decrease with an increase of the external magnetic field. In the weak magnetic field the corresponding efficiency at maximum power is slightly larger than the Curzon–Ahlborn (CA) efficiency, while in the large magnetic field it is obviously lower than CA efficiency.