The effect of Cr substitution on the structural, electronic and magnetic properties of pulsed laser deposited NiFe2O4 thin films

• Thin films of Ni1−xCrxFe2O4 are grown on Si(111) and Si(100) substrates.
• Films on Si(111) substrate are better crystalline than those on Si(100).
• XRD and FTIR results confirm the single phase growth of the films.
• Cationic distribution deviates from inverse spinel structure, as revealed by XPS.
• Saturation magnetization is larger on Si(100) but lower than the bulk value.

We have studied the structural, electronic and magnetic properties of pulsed laser deposited thin films of Ni1−xCrxFe2O4 (x=0.02 and 0.05) on Si (111) and Si (100) substrates. The films reveal single phase, polycrystalline structure with larger grain size on Si (111) substrate than that on Si (100) substrate. Contrary to the expected inverse spinel structure, x-ray photoemission (XPS) studies reveal the mixed spinel structure. XPS results suggest that Ni and Fe ions exist in 2+ and 3+ states, respectively, and they exist in tetrahedral as well as octahedral sites. The deviation from the inverse spinel leads to modified magnetic properties. It is observed that saturation magnetization drastically drops compared to the expected saturation value for inverse spinel structure. Strain in the films and lattice distortion produced by the Cr doping also appear to influence the magnetic properties.