Effect of Magnetic Field on Crystal Lattice in Dysprosium Studied by X-Ray Diffraction

A change of the c -lattice parameter of Dy which is induced by magnetic field along the easy direction of magnetization has been studied by X-ray diffraction in the temperature range of the helix phase. A discontinuous change of the c lattice parameter accompanying to the helix to fan or ferromagnetic transition has been observed below 170 K, but it becomes continuous change above 170 K to T N . The lattice modulation with the same wave number as the magnetic modulation has been observed at the distorted helix phase, which can be explained in terms of magnetoelastic effect.