Influence of local structure on the magnetism of MN-based novel Heusler alloys

Abstract

Since ancient times, magnetism has been known by humanity and has more than two millennia of recorded history [1]. Investigations of magnetic phenomena led to immense progress in our development: from needles and, horseshoes then to electromagnetics and eventually to a panoply of hard and soft magnetic materials which are the backbones of the technology today. It is mainly in the 20th century when the foundations of magnetism-based modern technology were laid as Curie and Weiss successfully described the phenomenon of spontaneous magnetization and its temperature dependence. Weiss postulated the existence of magnetic domains [2], and molecular field [3], thus providing an explanation for how a material could be magnetized, and nevertheless, have a net zero magnetization. Later, the properties of the magnetic domain walls were studied in detail by Bloch, Landau, and N`eel, paving the way to modern magnetism. At present, our investigations of magnetic phenomena are guided mainly by the need for more energy saving technologies; which also demand extensive work to achieve a basic understanding of different aspects of magnetism in condensed matter. On those grounds, discovering new magnetic materials and new magnetic spin-based experimental probes are more and more essential. Our main emphasis in this thesis work is on the fundamental aspects of different type of magnetic ground states seen in the intermetallic system known as Heusler alloy. This material system forms the basis for various applications-based properties and fits the criteria to be regarded as ‘ideal’ functional materials, with dominant strengths, and better temperature capabilities [4]. The emergence of diverse mag netic ground states/ electrical transport phenomena in a single material class clearly stresses the importance of studying the precise interplay between the several physical correlations at the atomic level and the structure of the system.