Addressing disorder: Modelling alloys and magnetic materials across length scales
Date:
Invited speaker for the Quantum Materials and Sensing Institute seminar series at Northeastern University.
Abstract
It is exceedingly rare for real-world materials to be as pristine as those considered in the examples to be found in the pages of our undergraduate textbooks. Indeed, a wide range of technologically relevant materials contain a degree of ‘disorder’ of some kind. Examples include glasses, where there is no well-defined underlying crystal lattice; alloys, where atoms of different chemical identities occupy lattice sites at random; and magnetic materials, where the effects of finite temperature cause magnetic moments first to ‘wobble’ and then to disorder entirely as a material enters its paramagnetic phase. It is crucial that modelling techniques are developed which can accurately simulate such disordered materials and provide insight into experimental studies.
In this talk, I will discuss means by which chemical and magnetic disorder can be studied computationally at the subatomic and atomic length scales via application of density functional theory (DFT) calculations, interatomic potentials, and machine learning techniques. Through application of methods from statistical physics, I will then demonstrate how it is then possible to extract quantities such as alloy disorder-order transition temperatures and materials’ magnetic critical temperatures, along with information about a range of other functional and structural properties, enabling links to be made with experiment. Example applications will include structural materials [1], high-entropy alloys [2], and rare-earth-free permanent magnets [3].
References
[1] L. Shenoy, C. D. Woodgate, J. B. Staunton, et al., Phys. Rev. Materials 8, 033804 (2024).
[2] C. D. Woodgate, D. Hedlund, L. H. Lewis, J. B. Staunton, Phys. Rev. Materials 7, 053801 (2023).
[3] C. D. Woodgate, C. E. Patrick, L. H. Lewis, J. B. Staunton, J. Appl. Phys. 135, 163905 (2023).