Fundamentals and Physical Properties of Heusler Alloys

This book presents a comprehensive investigation of the structural, electronic, elastic and magnetic properties of Heusler alloys through a combination of theoretical modelling and experimental investigation, with particular emphasis on their potential for advanced multifunctional technological applications.

The first part focuses on the X2CrSb alloys (X = Mn, Co, Cu), which were investigated using Density Functional Theory. The results reveal the significant influence of atomic composition, pressure and structural stability on their electronic and magnetic properties. In particular, Mn₂CrSb undergoes a pressure-induced structural transition whilst maintaining half-metallic behaviour and high spin polarisation under specific conditions. Co₂CrSb also retains its half-metallicity and high spin polarisation upon expansion, whereas Cu₂CrSb exhibits weaker spin polarisation. These characteristics highlight the potential of Mn₂CrSb and Co₂CrSb for spintronic applications, including magnetic random-access memory, magnetic tunnel junctions and spin valves, whilst the metallic character of Cu₂CrSb suggests potential applications in pressure- and strain-sensing technologies.

The book also presents an experimental investigation of the quaternary Heusler system Co(2-x)Fe(x)CrSn (x = 0, 0.5, 1). Structural and microscopic analyses reveal the formation of a primary hexagonal phase, accompanied by the emergence of a secondary cubic phase with partial Fe substitution. The stabilisation of a hexagonal phase in this quaternary system is an uncommon feature amongst Heusler compounds and provides valuable insight into the role of atomic substitution in controlling their structural and physical properties.

By combining computational predictions with experimental observations, this work provides a comprehensive insight into the versatility of Heusler alloys and their potential for the development of functional materials. The findings contribute to a deeper understanding of structure–property relationships and offer promising prospects for applications in spintronics, magnetic sensing and other emerging technologies.