Role of structural disorder in ferromagnetism of chromium-doped indium oxide

Structurally defective and highly crystallized chromium (Cr)-doped indium oxide samples are fabricated by rf sputtering. Both samples with 4% Cr doping show a very weak saturation magnetization of similar to 0.05 mu(B)/Cr. The magnetization of the structurally defective Cr-doped films as low as 2.8% is significantly enhanced to similar to 0.31 mu(B)/Cr (a six-fold increase), in contrast to only a two-fold increase in the magnetization of the highly crystallized samples. We use the bound magnetic polaron and charge-transfer free electron mediation models to explain the magnetization dependence on the ratio of lattice disorder-related electron concentration to Cr ion density.