Temperature dependence of Magnetic properties in Nanocrystalline copper ferrite thin films

The copper ferrite thin films have been deposited by RF sputtering at a 50W rf power. The As-deposited films are annealed in air at $800^{\circ}$C and then slow cooled. The As-deposited (AD) as well as slow cooled (SC) films are studied using a SQUID Magnetometer. The M Vs H curves have been recorded at various temperatures between 5K to 300K. The coercivities obtained from the MH curves are then plotted against temperature (T). The magnetization in the films does not saturate, even at the highest field of 7T. The high field part of the M Vs H curves is fitted using the H1/2 term of Chikazumi expression M(H)= Q*(1- a /Hn), with n=1/2. The variation of coefficient 'a' of H1/2 term has been observed with temperature (T). An attempt has been made to correlate this with the coercivity (Hc) in the case of annealed films.