Neutron and Magnetic Studies of a Single Crystal of Fe2TiO4

Abstract

Magnetic properties of a single crystal of almost pure Ulvospinel Fe 2.05 Ti 0.95 O 4.00 have been investigated by neutron diffraction and magnetic studies. Fe 2 TiO 4 is a perfect inverse spinel with oxygen parameter of u =0.386±0.001 at room temperature. The crystal becomes weakly ferromagnetic below 142°K. The magnetic structure is of the Neel type with the sublattice magnetic moments of 4.2±0.2µ B on both octahedral and tetrahedral sites at 4.2°K. The moment on the octahedral site decreases with increasing temperature faster than that on the tetrahedral site. The spontaneous weak ferromagnetic moment is induced in one of the direction perpendicular to spins. The spins tend to orient to the direction of the field, only when the magnetic field is applied in the [100] direction. The crystal is suggested to distort tetragonally at low temperatures with the spin along the long axis. The average \bar u parameter at 4.2°K is also 0.386±0.001.