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New insights into microstructural evolution of epitaxial Ni-Mn-Ga films on MgO (100) substrate by high-resolution X-ray diffraction and orientation imaging investigations

Sharma, Amit and Mohan, Sangeneni and Suwas, Satyam (2018) New insights into microstructural evolution of epitaxial Ni-Mn-Ga films on MgO (100) substrate by high-resolution X-ray diffraction and orientation imaging investigations. In: PHILOSOPHICAL MAGAZINE, 98 (10, A). pp. 819-847.

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Official URL: http://dx.doi.org/10.1080/14786435.2017.1418094

Abstract

In this work, a detailed investigation has been performed on hetero-epitaxial growth and microstructural evolution in highly oriented Ni-Mn-Ga (1 0 0) films grown on MgO (1 0 0) substrate using high-resolution X-ray diffraction and orientation imaging microscopy. Mosaicity of the films has been analysed in terms of tilt angle, twist angle, lateral and vertical coherence length and threading dislocation densities by performing rocking curve measurements and reciprocal space mapping. Density of edge dislocations is found to be an order of magnitude higher than the density of screw dislocations, irrespective of film thickness. X-ray pole figure measurements have revealed an orientation relationship of || 0 0 1](MgO) between the film and substrate. Microstructure predicted by X-ray diffraction is in agreement with that obtained from electron microscopy and atomic force microscopy. The evolution of microstructure in the film with increasing thickness has been explained vis-a-vis dislocation generation and growth mechanisms. Orientation imaging microscopy observations indicate evolutionary growth of film by overgrowth mechanism. Decrease in coercivity with film thickness has been explained as an interplay between stress field developed due to crystal defects and magnetic domain pinning due to surface roughness.

Item Type: Journal Article
Additional Information: Copy right for the article belong to TAYLOR & FRANCIS LTD, 2-4 PARK SQUARE, MILTON PARK, ABINGDON OR14 4RN, OXON, ENGLAND
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Division of Interdisciplinary Research > Centre for Nano Science and Engineering
Depositing User: Id for Latest eprints
Date Deposited: 14 Mar 2018 17:38
Last Modified: 14 Mar 2018 17:38
URI: http://eprints.iisc.ac.in/id/eprint/59180

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