Large Room Temperature Magnetic Moment in Mn${_{1-x}}$Zn${x}$Fe₂O₄Thin Films for

摘要

Mn_1-xZn_xFe₂O₄(0.1 ≤ x ≤ 0.8) thin films with nanocrystalline grains were deposited on amorphous quartz substrate using pulsed laser ablation technique, at a substrate temperature of 650 °C. For x ≤ 0.3, the room temperature spontaneous magnetization (4πM_S) of thin films was observed to be lower than the bulk composition. For x = 0.7, the room temperature 4πM_Svalue (~6.1 kG) is 7.5 times the bulk value for same x. This value is only 1.4 times of the bulk at 10 K, signifying a large enhancement in the exchange constant for thin films. The exchange stiffness constant (D) values were evaluated by fitting the 4πM_Sdata to the Bloch equation. The D values of thin films were always higher than that of the bulk. This result can be explained on the basis of occupancy of nonmagnetic Zn^{2+on both the tetrahedral (A) and octahedral (B) sites. This is unlike in the bulk, where all the Zn2+ions occupy only A site.}