Magnetic Properties of Tb–Ho Single-Crystal Alloys. I. Magnetization Measurements

We have investigated the magnetic properties of three single crystals of the Tb–Ho alloy system containing 10%, 50%, and 90% Ho from 4.2°–300°K in applied fields up to 28 kOe. Magnetic-moment measurements were made along the a 〈112̄0〉, b 〈101̄0〉, and c 〈0001〉 directions of the close-packed hexagonal structures. Within the limitations of such measurements we find that the Tb–Ho alloys exhibit similar characteristics to the pure metals. The trend upon increasing the concentration of Ho in Tb is to enhance and widen the antiferromagnetic region at the expense of the ferromagnetic region. The Néel temperatures and polycrystalline paramagnetic Curie temperatures decrease approximately linearly with Ho content to the pure Ho values. The absolute saturation moments in the basal plane and effective number of Bohr magnetons in the paramagnetic region increase linearly with Ho content. Anisotropy between the a and b directions is observed at low temperatures in all the alloys, with the b preferred. The c direction is the hard direction in all cases, although there is some evidence for a small amount of ordering along the c direction in the alloy containing 90% Ho.