Over 50% reduction in the formation energy of Co-based Heusler alloy films by two-dimensional crystallisation

Journal Article · Mon Jul 21 00:00:00 EDT 2014 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4886769· OSTI ID:22311145

Sagar, James; Fleet, Luke R.; Walsh, Michael; Whear, Oliver; Huminiuc, Teodor ^[1]; Lari, Leonardo ^[1]; Boyes, Edward D. ^[1]; Vick, Andrew ^[1]; Hirohata, Atsufumi ^[2]

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1. Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom)
2. Department of Electronics, University of York, Heslington, York YO10 5DD (United Kingdom)

Crystalline formation of high magnetic-moment thin films through low-temperature annealing processes compatible with current semiconductor technologies is crucial for the development of next generation devices, which can utilise the spin degree of freedom. Utilising in-situ aberration corrected electron microscopy, we report a 235 °C crystallisation process for a Co-based ternary Heusler-alloy film whose initial nucleation is initiated by as few as 27 unit cells. The crystallisation occurs preferentially in the 〈111〉 crystalline directions via a two-dimensional (2D) layer-by-layer growth mode; resulting in grains with [110] surface normal and [111] plane facets. This growth process was found to reduce the crystallisation energy by more than 50% when compared to bulk samples whilst still leading to the growth of highly ordered grains expected to give a high degree of spin-polarisation. Our findings suggest that the 2D layer-by-layer growth minimises the crystallisation energy allowing for the possible implementation of highly spin-polarised alloy films into current chip and memory technologies.

• OSTI ID: 22311145
• Journal Information: Applied Physics Letters, Vol. 105, Issue 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
COBALT COMPOUNDS
CRYSTAL GROWTH
CRYSTALLIZATION
CURRENTS
DEGREES OF FREEDOM
ELECTRON MICROSCOPY
FORMATION HEAT
HEUSLER ALLOYS
LAYERS
MAGNETIC MOMENTS
POLARIZATION
SEMICONDUCTOR MATERIALS
SPIN
SURFACES
THIN FILMS
TWO-DIMENSIONAL CALCULATIONS