Azimi, M., Chotorlishvili, L., Mishra, S. K., Vekua, T., Hübner, W., Berakdar, J.
Quantum Otto heat engine based on a multiferroic chain working substance
New Journal of Physics 16, (6),pp 063018/1-22 (2014)
We study a quantum Otto engine operating on the basis of a helical spin-1/2
multiferroic chain with strongly coupled magnetic and ferroelectric order parameters.
The presence of a finite spin chirality in the working substance enables
steering of the cycle by an external electric field that couples to the electric
polarization. We observe a direct connection between the chirality, the entanglement
and the efficiency of the engine. An electric-field dependent threshold
temperature is identified, above which the pair correlations in the system, as
quantified by the thermal entanglement, diminish. In contrast to the pair correlations,
the collective many-body thermal entanglement is less sensitive to the
electric field, and in the high temperature limit converges to a constant value. We
also discuss the correlations between the threshold temperature of the pair
entanglement, the spin chirality and the minimum of the fidelities in relation to
the electric and magnetic fields. The efficiency of the quantum Otto cycle shows
a saturation plateau with increasing electric field amplitude.
TH-2014-30