Pure Spin Current Phenomena

Spintronic phenomena and devices have evolved from exploiting spin-polarized current to pure spin current. A pure spin current can more efficiently deliver spin angular momentum with fewer or no charge carriers, enabling spin-orbit torque switching in ferromagnets. The prospects of antiferromagnetic spintronics, especially electrical switching, remain perplexing and controversial. We describe some recent advances, outstanding issues, challenges, and prospects of pure spin current.