Growth and Electronic Properties of Heusler Epitaxial Thin Films

Synopsis

Heusler compounds are an exciting family of ternary intermetallics that can be composed of elements from a large fraction of the periodic table. Their electronic properties are predicted to depend on the number of valence electrons per formula unit. In general, Heusler compounds form two main variants: half-Heuslers (XYZ) with the C1_b crystal structure and full-Heuslers (X₂YZ) with the L2₁ crystal structure. They have been predicted and experimentally shown to exhibit novel electronic and magnetic properties, such as half-metallic ferromagnetism, semiconducting and superconducting. A number of half-Heusler compounds are predicted to be topological non-trivial insulators or semimetals and should display topological surface states, which would be useful for spintronic applications.

The half-Heusler compounds with composition XYZ can be thought of as being a zincblende structure of XZ with the Y atoms in the octahedral sites. The close similarity to the zincblende III-V compound semiconductors and the ability to adjust the lattice parameters of III-V semiconductors by alloying over the range of lattice parameters of many Heusler compounds, makes III-V semiconductors a good choice as substrates for Heusler compound epitaxial growth.

In this presentation, I will emphasize the molecular beam epitaxial growth and properties of Heusler compounds grown on III-V semiconductors. Their application in spintronic devices will also be discussed.