Spin Axis Rotation in Hematite

Detailed measurements of m⊥, magnetization normal to the C axis, of pure synthetic hematite crystals as a function of H⊥ (0–20 kOe) and T (210°–273°K) indicate a 3 or more step process for rotation of the spin axis from the [111] AF or C axis, θ=0°, into the (111) WF plane, θ=90°, as H⊥ and/or T is increased. The rotation starts from θ=0° with a smooth change in θ, increasing in rate for higher T; this is followed by an abrupt jump, decreasing in amplitude for lower T, and finally as θ approaches 90° there is a smaller more gradual jump.