Magnetic structures of the rare earth orthotitanites RTiO 3; R = Tb, Dy, Tm and Yb

Abstract

The magnetic structures of the rare earth orthotitanites, RTiO 3, R = Tb, Dy, Tm and Yb, have been solved using neutron powder diffraction techniques. Two different types of magnetic structure have been found. One has the titanium and rare earth moments antiparallel along the c axis. The other structure has the rare earth moments in the ab plane with both ferromagnetic and antiferromagnetic components. In TbTiO 3, the terbium moment of (8.1 ± 0.4)μ β has ferromagnetic and antiferromagnetic components along the [100] and [010] directions, respectively, with the moments lying at an angle of (36 ± 3)° to the [100] direction. In DyTiO 3, the dysprosium moment of (9.7 ± 0.7)μ β has ferromagnetic and antiferromagnetic components along the [010] and [100] directions, respectively, with the moments making an angle of (31 ± 5)° to the [010] direction. TmTiO 3 has a thulium moment of (6.0 ± 0.4)μ β in a ferromagnetic array along the [001] direction. The average titanium moment in the orthotitanites is (0.7 ± 0.3)μ β in a direction antiparallel to the ferromagnetic component of the rare earth moment. The ytterbium moment in YbTiO 3 is quenched. It is found to be (1.7 ± 0.2)μ β assuming a moment direction along [001]. The rare earth moment directions are found to be remarkably consistent in the series RMO 3, M = Ti, Cr, Fe and Al.