Helimagnetic-ferromagnetic phase coexistence in MnP: a synchrotron radiation and neutron diffraction topography investigation

Neutron and white-beam synchrotron radiation topography have been used to observe the helimagnetic-ferromagnetic phase coexistence in single crystal MnP. The phase transition was approached by varying either the temperature or the magnetic field. The interface between the two phases displays a finely meshed zigzag shape with the 'needles' being directed along the easy axis of magnetization and arranged (when no external magnetic field is applied) around an average direction corresponding to a state of minimal elastic deformation. This morphology appears to result from competition between the elastic and magnetostatic terms of the total energy. The relative magnitudes of these terms are different for temperature- and field-induced transitions. The helimagnetic region is, in the field-driven case, expelled to the edges of the sample and forms a type of 'supplementary domain' pattern, the interface retaining its finely structured zigzag shape. (author)