Gate-voltage induced giant spin Seebeck effect in phosphorene nanoribbons

Using the tight-binding approximation combined with the mean-field Hubbard model and a Green's function approach, we designed a spin thermoelectric device in which the electrodes and the channel region consist of zigzag phosphorene nanoribbons. Our theoretical results show that applying a gate voltage only in the channel region induces a spin-semiconducting behavior with spin-polarized midgap states. Furthermore, the appearance of the localized and asymmetric electron-hole transmission coefficients induces a giant spin Seebeck effect with a spin-dependent current by applying a thermal gradient. Additionally, the spin-Seebeck values for zigzag phosphorene nanoribbons could be larger than those calculated for magnetized zigzag graphene nanoribbons. More interestingly, the values and the direction of the spin Seebeck effect as well as the spin-dependent currents can be easily manipulated by controlling the applied gate voltage or the magnetic state of the channel at room temperature.