Orbital anisotropy of the field-induced moments in chromium and vanadium

The dependence of the cross-section for magnetic scattering of neutrons on the angle θk between the field direction and the scattering vector has been used to study the orbital contribution to magnetic scattering from the moments aligned by a magnetic field in chromium and vanadium. The results lend support to band structure calculations which predict very high ratios of orbital to spin moments. The magnetic scattering from the moments induced in Cr and V by a 9.5 T field applied parallel to (110), in sets of crystallographically equivalent reflections having different values of θk, has been determined from polarized neutron flipping ratio measurements. The results have been analysed using the tensor operator formalism. The results do not show the equatorial anisotropy predicted by a simple atomic model in which the orbital moment arises from mixing between empty eg and filled t2g states. The azimuthal variation observed suggests that the major part of the orbital moment is due to 3d states with projections of angular momentum m = ±2