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

James Sagar, Luke R. Fleet, Michael Walsh, Leonardo Lari, Edward D. Boyes, Oliver Whear, Teodor Huminiuc, Andrew Vick, Atsufumi Hirohata

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Article number032401
JournalApplied Physics Letters
Issue number3
Publication statusPublished - 21 Jul 2014


  • UKRI
  • EP/H026126/1


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