Stoichiometry determined exchange interactions in amorphous ternary transition metal oxides: Theory and experiment

Amorphous transition metal oxides exhibit exotic transport and magnetic properties, while the absence of periodic structure has long been a major obstacle for the understanding of their electronic structure and exchange interaction. In this paper, we have formulated a theoretical approach, which com...

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Bibliographic Details
Published in:Journal of applied physics 2014-07, Vol.116 (4)
Main Authors: Hu, Shu-jun, Yan, Shi-shen, Zhang, Yun-peng, Zhao, Ming-wen, Kang, Shi-shou, Mei, Liang-mo
Format: Article
Language:English
Subjects:
AMORPHOUS STATE
Applied physics
COBALT COMPOUNDS
Computer simulation
COMPUTERIZED SIMULATION
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
ELECTRONIC STRUCTURE
EXCHANGE INTERACTIONS
Exchanging
FERROMAGNETISM
MAGNETIC PROPERTIES
MAGNETIZATION
Metal oxides
MICROSTRUCTURE
MONTE CARLO METHOD
Monte Carlo simulation
OXIDES
Oxygen
OXYGEN COMPOUNDS
Periodic structures
PERIODICITY
SEMICONDUCTOR MATERIALS
SPIN
Spin dynamics
STOICHIOMETRY
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
Transition metal oxides
Transition metals
Transport
ZINC COMPOUNDS
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Summary:Amorphous transition metal oxides exhibit exotic transport and magnetic properties, while the absence of periodic structure has long been a major obstacle for the understanding of their electronic structure and exchange interaction. In this paper, we have formulated a theoretical approach, which combines the melt-quench approach and the spin dynamic Monte-Carlo simulations, and based on it, we explored amorphous Co0.5Zn0.5O1−y ternary transition metal oxides. Our theoretical results reveal that the microstructure, the magnetic properties, and the exchange interactions of Co0.5Zn0.5O1−y are strongly determined by the oxygen stoichiometry. In the oxygen-deficient sample (y > 0), we have observed the long-range ferromagnetic spin ordering which is associated with the non-stoichiometric cobalt-rich region rather than metallic clusters. On the other hand, the microstructure of stoichiometric sample takes the form of continuous random networks, and no long-range ferromagnetism has been observed in it. Magnetization characterization of experimental synthesized Co0.61Zn0.39O1−y films verifies the relation between the spin ordering and the oxygen stoichiometry. Furthermore, the temperature dependence of electrical transport shows a typical feature of semiconductors, in agreement with our theoretical results.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4891474