Thermal hysteresis and domain states in Ni–Zn ferrites synthesized by oxalate precursor method

Nickel zinc ferrites with generic formula, Ni X Zn 1− X Fe2O4 (with X=0.28–0.40) were synthesized by an oxalate precursor route starting with acetates to study their magnetic properties. The saturation magnetization versus temperature curves resemble those of R type ferrites. The system shows the presence of Yafet–Kittel type of spin. It is observed that magnetic moment ( n B ) values increase with the addition of Ni 2+. The remanance ratio R tends to increase with the addition of Ni 2+, which has been attributed to the increase of magnetocrystalline anisotropy constant (K1). The values of R compare well with the theoretical value (0.87). The coercive force ( H c ) tends to increase with the addition of Ni 2+, which has been related to the reverse domain formation. Studies on temperature variation of R and H c reveal that these parameters are thermally insensitive, which confirms the presence of multi domain grains in the material. These observations have been supported by a.c. susceptibility studies.