Neutron and Magnetic Studies of a Single Crystal of Fe_2TiO_4

概要

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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_2TiO_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 <100> 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 u parameter at 4.2°K is also 0.386±0.001.
1971-08-05