Magnetization and magnetic susceptibility of single crystals of HoTiO3 and ErTiO3

Bulk magnetization measurements have been performed on single crystals of HoTiO3 and ErTiO3. The easy direction of magnetization is along the b-axis for HoTiO3 and along the c-axis for ErTiO3 with respect to the Pbnm chemical cell. These findings are in qualitative agreement with the results of two independent powder neutron diffraction studies. The saturation magnetic moments at 4.2 K along the easy axes are 7.3(2)μB per formula unit for HoTiO3 and 6.9(2)μB for ErTiO3. In addition, single crystal susceptibility data were analyzed using the theory of Boutron to yield values for the Heisenberg exchange coupling and the second-order crystal field terms B02 and B22.