Antiferromagnetism-assisted oblique-spin quantum entanglement

We theoretically study the antiferromagnetism-involved Andreev reflection (AR) in a graphene-based ferromagnet/superconductor/antiferromagnet hybrid structure, with the ferromagnetic exchange field rotated in the ferromagnet region. The local and nonlocal ARs are considerably characterized by the spin polarization of the antiferromagnet region. A switching effect of perfect spin-singlet nonlocal AR processes can be achieved by conversion from the parallel to the antiparallel configuration for the ferromagnetic and antiferromagnetic exchange fields. Particularly, under the noncollinear scenario, a quasiperfect oblique-spin nonlocal AR process can be realized. It could bring about novel spin quantum entanglement, which cannot be lost in the presence of only one stray field and has scarcely been explored thus far.