The magnetic spinel ferrite nanoparticle is exceptionally intriguing nanocrystal system due to the industrial importance of various technical applications and the scientific significance of studying the quantum origin of magnetism. Studies of quantum influences upon magnetic properties have revealed that the spin-orbit coupling and the net magnetization greatly affect the net magnetic properties of each spinel ferrite system differently. In case of cobalt ferrite where spin-orbit coupling is relatively large, increasing Cr³⁺ doping concentration, which has smaller magnetic moment and zero angular moment, decreases blocking temperature, saturation magnetization, remnant magnetization and coercivity. However, in case of manganese ferrite where spin-orbit coupling is relatively small, increasing Cr³⁺ doping concentration, reduces all the magnetic parameters except coercivity. The coercivity increases due to smaller magnetocrystalline anisotropy energy constant which forces the coercivity to increase as saturation magnetization decreases in accordance with Stoner-Wohlfarth theory. In order to improve product quality and quantity, synthesis routes in hot oleylamine and aminolytic reaction were developed. Both methods were proven to be extremely effective, environmental friendly, inexpensive, and simple routes in the synthesis of a variety of spinel ferrite systems including CoFe₂O₄, MnFe₂O₄, NiFe₂O₄, and ZnFe₂O₄ from a single source metal precursor.