Anomalous spin Josephson effect in ferromagnetic graphene with spin superconductivity

Abstract

We theoretically investigate the spin Josephson effect in spin superconductors based on the ferromagnetic graphene with noncollinear magnetic configurations. For the Josephson junctions with out-of-plane magnetization, the possible π-state spin supercurrent can be generated due to the Fermi momentum-splitting Andreev-like reflections at the normal metal/spin superconductor interfaces. For the Josephson junctions with in-plane magnetization, the anomalous spin supercurrent appears and is driven by the misorientation angle of the in-plane magnetization. The symmetry analysis shows that the appearance of the anomalous spin Josephson current is possible when the combined symmetry of the spin rotation and the time reversal is broken.