Cationic distribution, exchange interactions, and relaxation dynamics in Zn-diluted MnCo2O4 nanostructures

Pramanik, P and Joshi, DC and Tiwari, N and Sarkar, T and Pittala, S and Salman, OO and Manga, MM and Thota, S (2019) Cationic distribution, exchange interactions, and relaxation dynamics in Zn-diluted MnCo2O4 nanostructures. In: JOURNAL OF APPLIED PHYSICS, 125 (12).

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Abstract

We report an experimental investigation of the electronic structure and magnetic properties of bulk and nanosized MnCo2O4 diluted with Zn. The cationic distribution for tetrahedral A-site dilution is (Co1-yA2+ZnyA2+)(A)Mn3+Co3+](B)O-4 +/-delta, whereas B-site dilution results in (Co2+)(A)Mn1-xB3+ZnxB2+Co3+](B)O4-delta. The strength of exchange interaction J(ij) between the magnetic ions in a bulk spinel lattice decreases by similar to 15% for A-site dilution relative to the undiluted compound; however, B-site dilution results in an enhancement in J(ij) by 17%. The frequency and temperature dependence of dynamic-susceptibility chi(ac)(f, T)] studies of nanostructured compounds reveals the existence of spin-glass like behavior below the freezing temperature T-F similar to 125.7 K (for x(B) = 0.2) and 154.3 K (y(A) = 0.1). Relaxation time tau follows the Power-Law variation with a dynamical critical exponent zv = 6.17 and microscopic spin relaxation time tau(o) = 4.4 x 10(-15) s for x(B) = 0.2 (for y(A) = 0.1, zv = 5.2 and tau(o) = 5.4 x 10(-13) s). The amplitude and peak position in chi(ac)(T) decreases with an increase in the DC bias field, which indicates that the spin-glass phase can survive in the presence of low fields forming a critical line with an exponent 2/3. This behavior is similar to the de Almeida-Thouless (AT-line) analysis in the T-H phase diagram which supports the existence of spin-glass like behavior below T-F in these Zn diluted spinels. Published under license by AIP Publishing.

Item Type:	Journal Article
Publication:	JOURNAL OF APPLIED PHYSICS
Publisher:	AMER INST PHYSICS
Additional Information:	Copyright of this article belongs to AMER INST PHYSICS
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	17 May 2019 10:06
Last Modified:	17 May 2019 10:06
URI:	http://eprints.iisc.ac.in/id/eprint/62337

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