All optical ultrafast pure spin current in the altermagnet Cr 2 SO
The study demonstrated an all-optical route to generating pure spin current in Cr2SO, a 2d d-wave altermagnet. By combining ultrafast infrared valley excitation pulses with a THz pulse envelope, researchers achieved perfect charge cancellation while maintaining a large, pure spin current. This method leverages the vector potential of the THz field to tune valley excitations and exploit crystal momentum displacement to create dissipationless spin transport.