Thermoelectric effects of the single-spin state in the ferromagnetic-normal junction with artificial magnetic impurities

Abstract

We theoretically analyze the thermoelectric properties of the single-spin state based on the resonant tunneling of electron in the ferromagnetic-normal junction with artificial magnetic impurities. The thermoelectric coefficients, such as electrical conductance G, thermal conductance K, thermopower S and effective figure of merit Y, have been calculated using the nonequilibrium Green function in the linear regime. It is found that the thermoelectric coefficients can achieve considerable values by adjusting key parameters of the hybrid mesoscopic structure, such as the level detuning, the interdot hopping coefficient, the external magnetic field and the angle θ. When the level detuning changes, the spectra of electrical conductance and thermal conductance exhibit the electronic Dicke-like effect in the low temperature. Two valleys of electrical conductance and thermal conductance are always located at the single-spin level of QD2 ( and ), and can achieve the antiresonant point by adjusting the interdot hopping coefficient. Thermoelectric coefficients can achieve considerable values near valleys because the Wiedemann–Franz law is strongly violated. Thermopower S and effective figure of merit Y can get larger values in the vicinity of by adjusting key parameters of the hybrid mesoscopic structure, such as the level detuning, the interdot hopping coefficient and the polarization. But the thermoelectric effect is reversed by changing the angle θ. When the angle θ increases, S and Y are suppressed in the vicinity of meanwhile, S and Y are enhanced in the vicinity of shows that an electron in the state can virtually tunnel into the spin-up (or spin-down) state of the ferromagnet. The amplitude of electron tunneling is (or ). G and K decrease (or increase) as the angle θ increases in the vicinity of (or . So theoretical fundament is provided for the design of the single spin device.