All-in/all-out magnetic domains: X-ray diffraction imaging and magnetic field control

Long-range non-collinear all-in/all-out magnetic order has been directly observed for the first time in real space in the pyrochlore Cd$_2$Os$_2$O$_7$ using resonant magnetic microdiffraction at the Os L$_3$ edge. Two different antiferromagnetic domains related by time-reversal symmetry could be distinguished and have been mapped within the same single crystal. The two types of domains are akin to magnetic twins and were expected - yet unobserved so far - in the all-in/all-out model. Even though the magnetic domains are antiferromagnetic, we show that their distribution can be controlled using a magnetic field-cooling procedure.