Non-collinear spin in electronic structure calculations

AbstractNon-collinear spin materials are an exciting class of materials that are of great interest from both a fundamental materials science point of view and also with their possible applications in energy-efficient technological devices. Here we introduce non-collinear magnetism, in particular how to describe the electronic structure of materials with non-collinear magnetically ordered spin structures giving insight as to why it happens. Additionally, the use of electronic structure calculations is ubiquitous in current materials science research, commonly used by both theoretical and experimental researchers; we, therefore, detail how non-collinear magnetism is incorporated into the most commonly used electronic structure method, density functional theory.Keywords: Magnetismelectronic structurespintronicsdensity functional theory Disclosure statementNo potential conflict of interest was reported by the authors.Notes1 Here we will consider atomic magnetic dipoles, although more granular analogues exist where, for example, crystallites of a ferromagnetic material may bound together forming domains which interact magnetically.2 spin ℏ/2 or spin −ℏ/2.3 Other effects also split degeneracies, but they are not core to this discussion.4 Although ‘reasonable’ is subjective, the large number of DFT publications by both experts and non-experts in the field indicates it is often very reasonable.Additional informationNotes on contributorsS. J. ClarkS. J. Clark is a Professor of Physics at Durham University, specialising in theoretical and computational condensed matter physics. His interests lie in developing new methods in electronic structure theory and implementing them computationally, particularly for use in high-performance supercomputers. He is an author of the Castep code (www.castep.org) which is widely used in academia and industry for materials science research based on first-principles electronic structure methods.Z. HawkheadZ. Hawkhead received his PhD in Physics from Durham University where he specialised in non-collinear magnetic properties. His PhD thesis focused on first-principles calculations of exotic magnetic materials, as well as the implementation of new methods for non-collinear magnetism.