Implications of antiphase boundaries (APBs) on the strain relaxation and magnetotransport properties of Fe3o4 hetero-epitaxial thin films
Citation:
R.G. Sumesh Sofin, 'Implications of antiphase boundaries (APBs) on the strain relaxation and magnetotransport properties of Fe3o4 hetero-epitaxial thin films', [thesis], Trinity College (Dublin, Ireland). School of Physics, 2007, pp 256Download Item:
Abstract:
The strain relaxation and magneto transport properties of epitaxial
magnetite (Fe3O4) thin films were studied. Epitaxial Fe3O4 film s were grown
on MgO and MgAl2O4 substrates using an Oxygen plasma assisted Molecular
beam epitaxy (MBE) system. Characterisation of the films were done using
techniques such as Reflection high energy electron diffraction (RHEED), High
resolution X-ray diffractom eter (HRXRD), Vibrating sample magnetometer
(VSM), Low temperature resistivity measurements, and Raman Spectroscopy.
Our studies on strain relaxation behaviour of epitaxial Fe3O4 thin films grown
on MgO (100) substrates reveal that the films do not exhibit strain relaxation
up to 700 nm thickness, which is much larger than the strain relaxation critical
thickness, tc, (70nm) predicted by the most accepted model based on mismatch
strain. In contrast, the model predictions of strain relaxation behaviour are
consistent with our results for Fe3O4 films grown on MgAl2O4 (100). The
observed anomalous strain relaxation behaviour is attributed to the presence of
antiphase boundaries (APBs) which lead to the formation of areas within the
film that have opposite sign of stress. The stress compensation by the APBs
reduces the effective stress experienced by the films. Even though APBs are
not expected in Fe3O4 films grown on MgAl2O4, TEM studies revealed the
presence of APBs. We suggest that these APBs are formed not because of
symmetry difference but because of the staking faults generated by strain
relaxation due to the large mismatch between the thin film and substrate.
Author: Sofin, R.G. Sumesh
Advisor:
Shvets, IgorPublisher:
Trinity College (Dublin, Ireland). School of PhysicsNote:
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Physics, Ph.D., Ph.D. Trinity College DublinMetadata
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