# Characterization of L21 order in Co2FeSi thin films on GaAs

## TL;DR

This study investigates the structural order in Co2FeSi thin films grown on GaAs substrates, revealing inhomogeneous L21 and B2 phases, with up to 65% L21 order, using TEM and XRD techniques.

## Contribution

It provides detailed characterization of L21 order in Co2FeSi films on GaAs, highlighting inhomogeneities and diffusion effects affecting long-range order.

## Key findings

- Average L21 order up to 65% measured by XRD
- Inhomogeneous distribution of phases observed
- Correlation between Co/Fe ratio and order variations

## Abstract

Co2FeSi/GaAs(110) and Co2FeSi/GaAs(-1-1-1)B hybrid structures were grown by molecular-beam epitaxy (MBE) and characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The films contain inhomogeneous distributions of ordered L21 and B2 phases. The average stoichiometry could be determined by XRD for calibration of the MBE sources. Diffusion processes lead to inhomogeneities, influencing long-range order. An average L21 ordering of up to 65% was measured by grazing-incidence XRD. Lateral inhomogeneities of the spatial distribution of long-range order in Co2FeSi were imaged using dark-field TEM with superlattice reflections and shown to correspond to variations of the Co/Fe ratio.

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Source: https://tomesphere.com/paper/1907.05869