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Title: Tuning of magnetic transition temperatures in nanoparticles of CoCr{sub 2}O{sub 4} multiferroic by B-site mixing

Highlights: • Pure CoCr{sub 2−x}Fe{sub x}O{sub 4} (x = 0.1 and 0.2) nanoparticles of 16–20 and 6–10 nm show enhancement of T{sub c} from 100 to 110 K and T{sub s} from 18 K to 36 K with increasing Fe. • The theoretical variation of reciprocal susceptibility with temperature in paramagnetic region using the function χ{sup −1} = T/C + 1/χ{sub 0} – b/(T − θ) is fitted with the experimental data. • The difference in ferrimagnetic Curie point, θ{sub f} and paramagnetic Curie point, θ{sub p} is 30 K and 7 K respectively for sample x = 0.1 and 0.2 indicating a sharp ferri- to para-magnetic transition in the former one. - Abstract: Pure CoCr{sub 2−x}Fe{sub x}O{sub 4} nanoparticles synthesized through conventional coprecipitation technique show particle size distribution in the range of 16–20 and 6–10 nm for x = 0.1 and 0.2 respectively. Magnetic and specific heat measurements show an enhancement of paramagnetic to collinear ferrimagnetic transition temperature, T{sub c} from 100 to 110 K and to a short range non-collinear spiral ordering, T{sub s} from 18 to 36 K with increasing x from 0.1 to 0.2 respectively. In addition, a strong disagreement between the paramagnetic moment obtained frommore » the fitting of χ{sup −1} = T/C + 1/χ{sub 0} – b/(T − θ) and ferrimagnetic moment measured from the M vs. H loop at 10 K corroborates the nonsaturation behavior of magnetization at 50–100 kOe field and an order of magnitude higher coercivity (H{sub c}). The enhancement of T{sub c} and T{sub s} with increasing Fe concentration is attributed to an intrinsic change in non-collinear to collinear spin structure and strong J{sub A–B} interaction.« less
Authors:
; ; ;  [1] ; ;  [2] ;  [1]
  1. School of Materials Science and Technology, Indian Institute of Technology (BHU), Varanasi, 221005 (India)
  2. UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore, 452001 (India)
Publication Date:
OSTI Identifier:
22348661
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 54; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; CHROMITES; COERCIVE FORCE; ELECTRON DIFFRACTION; INTERACTIONS; MAGNETIC MATERIALS; MAGNETIC PROPERTIES; MAGNETIZATION; NANOPARTICLES; PARAMAGNETISM; PARTICLE SIZE; PHOTOELECTRON SPECTROSCOPY; SYNTHESIS