Characterization of structure and magnetism in Zn1-x(Co-x/Mn-x)O epitaxial thin films as a function of composition

Negi, D.S. and Loukya, B. and Dileep, K. and Kesaria, Manoj and Kumar, N. and Dutta, R. (2013) Characterization of structure and magnetism in Zn1-x(Co-x/Mn-x)O epitaxial thin films as a function of composition. Superlattices and Microstructures, 63. pp. 289-297. ISSN 0749-6036

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Abstract

We have investigated the non-equilibrium solubility of Mn and Co in Zn1-xTMxO (x = 5-30 at.% TM = Co, Mn) single crystal thin film and the role of Co/Mn concentration on the structural and magnetic properties. The films have been grown by pulsed laser deposition and the structural and magnetic characterization has been performed using high resolution transmission electron microscopy and superconducting quantum interference device respectively. Cobalt shows high solubility in single crystalline ZnO films with no tendency to form incoherent secondary precipitates up to 30 at.%. Whereas for Mn:ZnO, secondary precipitate started forming from Mn concentration of 25 at.% and above. HREELS of both Co and Mn L-2,L-3 absorption edges shows that the Co and Mn atoms have substituted the Zn positions in the lattice. ZnO doped with 30 at.% Mn forms single crystalline spinel Mn3O4 phase on the sapphire substrate in the form of an interlayer which is responsible for aligning subsequent Mn:ZnO film with respect to sapphire as [11-20]Al2O3 vertical bar vertical bar [11-20] ZnO compared to the usual [11-20]Al2-O3 vertical bar vertical bar[01-10] ZnO orientation. Saturation magnetization remained almost the same similar to 10(20)-10(21) mu(B)/cm(3)) for Co:ZnO but a composition dependent coercivity has been observed. For Zn0.75CO0.25O film, the coercivity is similar to 922 (769) Oe corresponding to applied field perpendicular (parallel) to the c axis, which is the highest value reported in this system. For Mn:ZnO ferromagnetism disappears beyond Mn concentrations of 15 at.%. (C) 2013 Elsevier Ltd. All rights reserved.

Item Type:
Journal Article
Journal or Publication Title:
Superlattices and Microstructures
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100/3104
Subjects:
ID Code:
68630
Deposited By:
Deposited On:
18 Feb 2014 09:49
Refereed?:
Yes
Published?:
Published
Last Modified:
01 Jan 2020 08:50