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Surface Spins Pinning Effect on the Magnetic Properties in Co3O4 Nanocrystallites Covered with Polymer Decomposition Residues |
| LI Shan-Dong;BI Hong;FANG Jiang-Lin;ZHONG Wei;DU You-Wei |
| 1National Laboratory of Solid State Microstructure and Department of Physics, Nanjing University, Nanjing 210093
2College of Chemistry and Chemical Engineering, Anhui University, Hefei 230039
3Center for Materials Analysis, Nanjing University, Nanjing 210093
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| Cite this article: |
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LI Shan-Dong, BI Hong, FANG Jiang-Lin et al 2004 Chin. Phys. Lett. 21 737-740 |
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Abstract We prepare two kinds of Co3O4 antiferromagnetic nanocrystallite systems with different surface structures: one grain surface is covered by polymer decomposition residues (PDRs) (referred to as CS) and the other is naked (NS). It has been found that the magnetic properties of the CS sample deviate greatly from those of the NS sample. For example, the CS sample exhibits an open loop up to 8 T at 4.2 K, while the two branches of the hysteresis loop for the NS sample superpose together when the field is in excess of 3 T. The average permanent magnetic moments per Co3O4 cell for the CS sample are about three times larger than that of the NS sample. The coercivity and loop shift for the CS sample are enhanced remarkably in comparison with the NS sample, i.e., from 73.8 and 11.0 kA/m for the NS sample to 116.5 and 25.5 kA/m for the CS sample, respectively. The anomalous magnetic properties and their enhancements for the CS sample are attributed to the surface spin pinning effect by PDRs.
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| Keywords:
75.75.+a
75.50.Ee
75.30.Et
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Published: 01 April 2004
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