Detecting Spin Heat Accumulation by Sign Reversion of Thermopower in a Quantum Dot Side-Coupled to Majorana Bound States

Abstract

We propose a scheme to detect the spin heat accumulation (SHA), an effective spin-dependent electron temperature, via sign reversion of thermopower induced by the Majorana bound states (MBSs) coupled to a quantum dot (QD). The SHA is generated in either a nonmagnetic material or a ferromagnet serving as an electrode connected to the QD and leads the spin-up and spin-down thermopowers to change signs at different temperatures with the help of QD-MBSs coupling. The existence of the SHA then can be detected by the variation of the spin-polarized or even charge thermopower with respect to the magnitude of the SHA. Our numerical results show that the transition temperature of the thermopower is sensitive to QD-MBSs coupling strength, hybridization between the MBSs, and the ferromagnetism on the leads. Around the transition temperature, either 100% spin-polarized or pure spin thermopower can be generated by the combined effects of SHA and MBSs. We also find that the intradot Coulomb interaction does not change the qualitative results of the present scheme.