Pure thermal spin current and perfect spin-filtering with negative differential thermoelectric resistance induced by proximity effect in graphene/silicene junctions

Abstract

The spin-dependent Seebeck effect (SDSE) and thermal spin-filtering effect (SFE) are now considered as the essential aspects of the spin caloritronics, which can efficiently explore the relationships between the spin and heat transport in the materials. However, there is still a challenge to get a thermally-induced spin current with no thermal electron current. This paper aims to numerically investigate the spin-dependent transport properties in hybrid graphene/silicene nanoribbons (GSNRs), using the nonequilibrium Green’s function method. The effects of temperature gradient between the left and right leads, the ferromagnetic exchange field, and the local external electric fields are also included. The results showed that the spin-up and spin-down currents are produced and flow in opposite directions with almost equal magnitudes. This evidently shows that the carrier transport is dominated by the thermal spin current, whereas the thermal electron current is almost disappeared. A pure thermal spin current with the finite threshold temperatures can be obtained by modulating the temperature, and a negative differential thermoelectric resistance is obtained for the thermal electron current. A nearly zero charge thermopower is also obtained, which further demonstrates the emergence of the SDSE. The response of the hybrid system is then varied by changing the magnitudes of the ferromagnetic exchange field and local external electric fields. Thus, a nearly perfect SFE can be observed at room temperature, whereas the spin polarization efficiency is reached up to 99%. It is believed that the results obtained from this study can be useful to well understand the inspiring thermospin phenomena, and to enhance the spin caloritronics material with lower energy consumption.

Vacancy tuned thermoelectric properties and high spin filtering performance in graphene/silicene heterostructures

“…The thermoelectric performance of nanostructures can also be enhanced by various ways, such as hybridization 31 , 32 , defects 33 – 35 , and doping 36 , 37 . As shown in the previous studies 4 , 38 , 39 , the hybrid nanostructures theoretically show superior thermoelectric properties than the similar materials with the single nanostructures. Several studies have already been performed to investigate various properties of the GSNRs in which GE and SE have vertically or laterally bonded together 40 – 43 .…”

“…The results showed that the combination of GE with other 2D materials could lead to a hybrid structure with various properties and applications 44 – 47 . Nevertheless, there are little data about the electronic behavior, spin transport, and thermoelectric attributes of the GSNRs 38 , 46 , and further research is still required in this area.…”

Tuning the spin caloritronic transport properties of InSe monolayers via transition metal doping

“…4–7 Clearly, spin caloritronics provides an alternative strategy for waste heat recovery and low-power consumption technology. 8,9 To date, many investigations have demonstrated that various candidates, such as single molecular magnets, metallic clusters, zigzag silicene and graphene nanoribbons, hybrid graphene/silicene nanoribbons, and magnetic tunneling heterojunctions, 10–17 hold great promise in spin caloritronics. 18 For example, due to the proximity effect, Gholami et al reported that the pure thermal-driven spin current through hybrid graphene/silicene nanoribbons can be modulated via changing the temperature bias, and then predicted the nearly perfect spin-filtering effect and the negative differential thermoelectric resistance.…”

“…18 For example, due to the proximity effect, Gholami et al reported that the pure thermal-driven spin current through hybrid graphene/silicene nanoribbons can be modulated via changing the temperature bias, and then predicted the nearly perfect spin-filtering effect and the negative differential thermoelectric resistance. 15…”

Proximity-induced spin-polarized magnetocaloric effect in transition metal dichalcogenides

“…We also analyze the effect of the Rashba field, showing that it enhances the cooling effects in the valence band. The generic existence of spin-polarized TMD electronic states given by TRS breaking that can be accessed by gating, suggests that these hybrid systems could be used as tunable thermal spin filters [37] for functional applications.…”