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Title: Hexagonal CoO nanoparticles as studied by electron spin resonance

We report the electron spin resonance (ESR) results of hexagonal CoO nanoparticles those are different in average size. The temperature evolution of ESR spectra was found to be complicated in nature. The anomalous ESR behaviour is ascribed to (i) uncompensated magnetic sublattice, (ii) magnetic anisotropy of nanoparticles, and (iii) spatial distribution of the anisotropy axis with respect to the magnetic field. Anomalous changes of resonance field and linewidth were observed near the Néel temperature, T{sub N}. According to the temperature dependence of ESR intensity, the T{sub N} values are found to be 225, 255, and 285 K for hexagonal CoO nanoparticles with sizes of 38, 49, and 67 nm, respectively. We found that the size dependence of T{sub N} fits well with the Boltzmann curve.
Authors:
; ;  [1]
  1. National Laboratory of Solid State Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Department of Physics, Nanjing University, Nanjing 210093 (China)
Publication Date:
OSTI Identifier:
22412989
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; COBALT OXIDES; DIAGRAMS; ELECTRON SPIN RESONANCE; HEXAGONAL LATTICES; MAGNETIC FIELDS; NANOPARTICLES; NEEL TEMPERATURE; SPATIAL DISTRIBUTION; TEMPERATURE DEPENDENCE