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|Title:||Size dependence of magneto-resistive behaviour of nano-particle magnetite|
|Authors:||Choudhary, B L|
Srivastava, Bipin K
|Abstract:||Two nano-particle samples of magnetite have been prepared with average particle sizes of ~260Å and ~1000Å. Electrical resistance of these samples has been measured in the temperature range 20-300 K and in magnetic fields up to 7.5 kOe. The two samples exhibit insulating/semi-conducting behaviour at all the temperatures. They show large magnetoresistance (MR). For the bigger particle’s sample MR is 23% at 300 K and 7.5 kOe at 40 K, the value drops to ~4%. For the smaller particle’s sample, MR is only ~4% at 300 K and shows slight increase to ~6% at 40 K. Results are suggestive of the pre-dominance of the polarized spin dependent contribution to resistivity. Observed features could be interpreted in terms of large magnetic anisotropy for surface spins of the nano-particles.|
|ISSN:||0975-1041 (Online); 0019-5596 (Print)|
|Appears in Collections:||IJPAP Vol.49(03) [March 2011]|
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