Observation of ferrotoroidic domains

Ferrotoroidicity goes fourth The defining property of ferroic materials — that's the ferromagnets, ferroelectrics and ferroelastics — is that of forming domains, based on magnetization, electric polarization and elastic strain respectively. It makes these materials of great technological importance, for instance in data storage as ferroelectric memory or as ferromagnetic domains written on a hard disk. But a fourth form of ferroic order has been postulated, based on an ordered arrangement of magnetic vortices or 'toroidization'. One of the prerequisites for this fourth form — called ferrotoroidicity — has now been observed , in the form of domains of opposite ferrotoroidic orientation. The ferrotoroidic domains were observed optically on lithium cobal phosphate (LiCoPO4), coexisting with independent antiferromagnetic domains. The ferrotoroidic state differs from the other forms of ferroic order in its asymmetric behaviour under the reversal of time and space. This asymmetry could lead to exciting possibilities for future applications.