Effect of Growth Temperature on the Magnetic, Microwave, and Cation Inversion Properties on NiFe2O4 Thin Films Deposited by Pulsed Laser Ablation Deposition
First principles band structure calculations suggest that the preferential occupation of Ni{sup 2+} ions on the tetrahedral sites in NiFe{sub 2}O{sub 4} would lead to an enhancement of the exchange integral and subsequently the Neel temperature and magnetization. To this end, we have deposited NiFe{sub 2}O{sub 4} films on MgO substrates by pulsed laser deposition. The substrate temperature was varied from 700 to 900 {sup o}C at 5 mTorr of O2 pressure. The films were annealed at 1000 {sup o}C for different times prior to their characterization. X-ray diffraction spectra showed either (100) or (111) orientation with the spinel structure dependent on the substrate orientation. Magnetic studies showed a magnetization value of 2.7 kG at 300 K. The magnetic moment was increased to the bulk value as a result of postdeposition annealing at 1000 {sup o}C. The as produced films show that the ferromagnetic resonance linewidth at 9.61 GHz was 1.5 kOe, and it was reduced to 0.34 kOe after postannealing at 1000 {sup o}C. This suggests that the annealing led to the redistribution of Ni{sup 2+} ions to their equilibrium octahedral sites. Further, it is shown that the magnetically preferred direction of H{sub a} can be aligned perpendicular to the film plane when films are grown with a fixed oxygen pressure of 5 mTorr for films deposited at 700 and 900 {sup o}C.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 930513
- Report Number(s):
- BNL-80483-2008-JA; JAPIAU; TRN: US200904%%567
- Journal Information:
- Journal of Applied Physics, Vol. 101; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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