Huge self-spin swapping effect with asymmetric spin-sink structures

The spin swapping effect is a promising phenomenon that provides a symmetry-breaking component for deterministic field-free switching, essential for the all-electric control of spintronic devices. Without the need for additional magnetic layers in the original proposal, this effect can occur with a single magnetic layer by reinjecting spin current back into itself, known as the self-spin swapping effect. Here, we experimentally demonstrate that the self-spin swapping effect is significant and even surpasses other dominant phenomena such as the spin Hall effect. This observation became possible by introducing two distinct setups with opposite parities between the self-spin swapping and spin Hall effects. These setups allowed us to observe a clear fingerprint of the self-spin swapping effect. By manipulating the structural inversion asymmetry using spin-swapping and spin-sink layers, we engineered the self-spin swapping effect to exceed the strength of the spin Hall effect. Our work not only provides a way to investigate the self-spin swapping effect quantitatively but also offers a method to engineer field-free switching in simplified stacking structures with fewer magnetic layers.