The magnetic properties of the rare earth titanium oxides RTiO(3); R = terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium

Abstract

<p>The magnetic properties of the heavy rare earth titanium oxides RTiO₃, R=Tb, Dy, Ho, Er, Tm, Yb and Lu, have been investigated. The RTiO₃ develop a spontaneous magnetization below critical temperatures ranging from 28 K to 64 K. Both the rare earth and titanium moments order at the same temperature. The field dependence of the magnetization at 4.2K indicates that the magnetocrystalline anisotropy is very large. The paramagnetic susceptibility of the materials formed with R=Tb-Tm is analyzed with molecular field theory to obtain the molecular field coupling constants λTi-Ti, λR-Ti and λR-R. The magnetic structures are determined for RTiO₃, R=Tb-Tm with the technique of neutron diffraction. The erbium and thulium moments form a ferromagnetic array along the orthorhombic c cxis and the terbium, dysprosium and holmium moments have both ferromagnetic and antiferromagnetic components in the ab plane, giving rise to a canted structure. The titanium moments are in a ferromagnetic array which is directed antiparallel to the ferromagnetic component of the rare earth moment. The preferred direction of the rare earth magnetization with respect to the orthorhombic c axis is discussed in terms of the interaction between 4f electrons on the rare earth and the crystalline environment. Calculations are presented which support this hypothesis.</p>