  Electrical and optical pulsing allow for manipulating the order parameter and
magnetoresistance of antiferromagnets, opening novel prospects for digital and
analog data storage in spintronic devices. Recent experiments in CuMnAs have
demonstrated giant resistive switching signals in single-layer
antiferromagnetic films together with analog switching and relaxation
characteristics relevant for neuromorphic computing. Here we report
simultaneous electrical pulsing and scanning NV magnetometry of
antiferromagnetic domains in CuMnAs performed using a pump-probe scheme. We
observe a nano-scale fragmentation of the antiferromagnetic domains, which is
controlled by the current amplitude and independent on the current direction.
The fragmented antiferromagnetic state conserves a memory of the pristine
domain pattern, towards which it relaxes. Domain fragmentation coexists with
permanent switching due to the reorientation of the antiferromagnetic moments.
Our simultaneous imaging and resistance measurements show a correlation between
the antiferromagnetic domain fragmentation and the largest resistive switching
signals in CuMnAs.
