Rathi, A. and Babu, P. D. and Rout, P. K. and Awana, V. P. S. and Tripathi, Vikash K. and Nagarajan, R. and Sivaiah, B. and Pant, R. P. and Basheed, G. A. (2019) Anomalous nano-magnetic effects in non-collinear spinel chromite NiCr2O4. Journal of Magnetism and Magnetic Materials, 474. pp. 585-590. ISSN 0304-8853

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Abstract

We present the results of a detailed investigation of magnetism in spinel chromite NiCr2O4 magnetic nanoparticles (MNPs). Compared to the bulk NiCr2O4, the finite crystallite size of about 10 nm lowers the Jahn-Teller distortion and greatly enhances the collinearity of the spin structure in MNPs with considerably reduced "frustration index" = vertical bar theta(CW)vertical bar/T-c. This leads to (longitudinal) ferrimagnetic ordering at much higher temperature, T-c approximate to 100 K and suppression of (transverse) antiferromagnetic ordering in MNPs (cf. T-c similar or equal to 65 K and T-s similar or equal to 30 K in the bulk); a transition to the cluster spin glass state occurs at T-g = 19.0 K. Moreover, the M-H hysteresis loops show anomalous "hour-glass" behavior at fields near H-c in the vicinity of T-g; this non-monotonous H-c (T) variation can not be accounted from the celebrated Stoner-Wohlfarth model. The present study interprets the anomalous H-c (T) behavior in the framework of magnetically interacting core-shell structure with large surface anisotropy, and points out the importance of surface effects in nanochromites compared to their counterpart ferrites.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Elsevier.
Subjects:	Materials Science Applied Physics/Condensed Matter
Divisions:	UNSPECIFIED
Depositing User:	Mr. Yogesh Joshi
Date Deposited:	24 Jan 2020 11:41
Last Modified:	24 Jan 2020 11:41
URI:	http://npl.csircentral.net/id/eprint/4107

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