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Title: Investigation of cation distribution, electrical, magnetic properties and their correlation in Mn{sub 2-x}Co{sub 2x}Ni{sub 1-x}O{sub 4} films

X-ray photoelectron spectroscopy was performed on Mn{sub 2-x}Co{sub 2x}Ni{sub 1-x}O{sub 4} (x = 0.2, 0.4, 0.5, 0.6, and 0.8) series spinel films to determine their cation distributions. The results show that both Ni and Co ions exhibit bivalence, while Mn ions exhibit coexisting multivalence. The hopping frequency ν{sub 0} of each sample was obtained by combining cation distribution results and electrical measurement data. Analysis of the divergence at Neel temperature between field cooling and zero-field cooling magnetization curves revealed that the ferromagnetic coupling between octahedral site ions first leads to spontaneous magnetization at T{sub C}, after which a second spontaneous magnetization arises from the antiferromagnetic couple between tetrahedral and octahedral sites at a lower temperature T{sub N}. The correlation between hopping conductivity and magnetic transition temperature is discussed. We propose that the strength of the ferromagnetic couple between octahedral sites is subject to the product term of Nc(1 − c)ν{sub 0}, which determines the ferromagnetic transition temperature (T{sub C}) of the system. Our results provide an avenue to understand the origin of magnetic interaction in small-polaron hopping semiconductors.
Authors:
; ; ; ;  [1] ;  [2] ; ;  [1] ;  [3]
  1. National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yu Tian Road, Shanghai 200083 (China)
  2. (China)
  3. No.3 Department, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yu Tian Road, Shanghai 200083 (China)
Publication Date:
OSTI Identifier:
22271197
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 11; Other Information: (c) 2014 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; ANTIFERROMAGNETISM; CATIONS; COBALT COMPOUNDS; COBALT IONS; CONCENTRATION RATIO; CORRELATIONS; FERROMAGNETISM; FILMS; MAGNETIC PROPERTIES; MAGNETIZATION; MANGANESE COMPOUNDS; MANGANESE IONS; NEEL TEMPERATURE; NICKELATES; SEMICONDUCTOR MATERIALS; X-RAY PHOTOELECTRON SPECTROSCOPY