The determination of magnetic structures using low temperature nuclear orientation:166mHo-Ho

It is demonstrated that the low temperature nuclear orientation technique can be used to determine the axes of quantization in a multiaxial ordered ensemble of nuclear spins. Expressions for the anisotropic ?-ray intensity from particular geometries are derived for the case in which each subsystem has its own axial symmetry. The determination of the atomic magnetic structure in antiferromagnets is discussed and the results of recent experiments on helically ordered^166mHo-Ho are presented. In these experiments, the angular variation of the intensities of some of the more intense ?-rays were measured and compared to theory. A value of 80.4(1)°, not including systematic errors, was obtained for the semi-cone angle of the helix formed by the atomic magnets.