Heat generation by spin-polarized current in a quantum-dot spin battery

We study the heat generation by spin-polarized current due to the electron-phonon coupling in a singlelevel quantum-dot, which is connected to an external either symmetric or asymmetric dipolar spin battery. We find that the heat generation depends sensitively on the configuration of the spin battery's chemical potentials. In the case of the dot coupled to symmetric spin battery, there is remarkable negative differential of the heat generation, which disappears if the spin battery is asymmetric. We also find that the magnitude of the heat generation in asymmetric spin battery is much larger than that in symmetric one despite of the reduced intensity of the electric current. Moreover, the heat generation is insensitive to the system's temperature, and develops peaks when the dot-lead coupling strength or the intradot Coulomb interaction approaches the phonon's energy quanta. (C) 2014 Elsevier B.V. All rights reserved.