Structural, electrical, and magnetic properties of Mn _2.52-xCo_xNi_0.48O₄ films

The serial films of Mn_2.52-xCo_xNi _0.48O₄ (x=0, 0.32, 0.64, and 0.96) with fixed Ni content of 0.48 are prepared on amorphous Al₂O₃ substrate by chemical solution deposition method. The x-ray diffraction and microstructure analyses indicate that Co/Mn content ratio can modify the preferred crystalline growth direction and the microstructure morphology of different composition is different under the same growth condition. The distribution of the cations for the four compositions is estimated based on the lattice constant and cation radii. The dc resistivity measurements demonstrate our speculation of the cation distributions. The electrical and magnetic measurements show that the thermal activation energy decreases but the ferrimagnetic transition temperature increases with the increase in Co content. The magnetization loop tests indicate that Mn_2.52-xCo_xNi_0.48O₄ serial films probably possess magnetic anisotropy with 〈 111 〉 magnetically easy axis.