Studies of magneto-electric crystals using spherical neutron polarimetry

Spherical neutron polarimetry provides a new tool for the study of magneto-electric crystals since it allows the rotation of scattered polarisation, characteristic of this class of crystal to be measured. Measurement of this rotation not only allows the relative populations of the magneto-electric domains to be determined, but also permits precise determination of the antiferromagnetic structure factors and hence of the magnetisation distribution leading to magneto-electricity. The method was initially applied to Cr2O3; in the present article we describe its use to study other magneto-electric crystals including LiCoPO4 and MnGeO3.