Spin caloritronics in two-dimensional CrI3/NiCl2 van der Waals heterostructures

Abstract

Two-dimensional van der Waals (vdW) heterostructures have recently emerged as attractive candidates to work as spintronic and optoelectronic devices. Here, two types of magnetic ${\mathrm{CrI}}_{3}/{\mathrm{NiCl}}_{2}$ vdW heterostructures are constructed to design spin caloritronic devices. The first-principles calculations uncover that the magnetic configurations of ${\mathrm{CrI}}_{3}/{\mathrm{NiCl}}_{2}$ vdW heterostructures can be converted easily to a ferromagnetic, an antiferromagnetic, and even a bipolar magnetic semiconducting state by an external electric field. More interestingly, two thermal spin-dependent currents with opposite spin orientations can be driven by a temperature gradient to flow in opposite transport directions independently in the different layers of vdW heterostructures, demonstrating that the ${\mathrm{CrI}}_{3}/{\mathrm{NiCl}}_{2}$ vdW heterostructures can exhibit a nearly perfect thermal spin-filtering effect in each layer while generating a well-defined spin-Seebeck effect in the whole system. Our work puts forward a class of material candidates to design spin caloritronic devices characterized by multiple inspiring thermal-spin transport behaviors.