Regensburg 2025 – wissenschaftliches Programm

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TUT: Tutorien

TUT 4: Tutorial: Do it Yourself Guide for Simulating Complex Magnetism: From Theoretical Foundations to Hands-on Spin-dynamics (joint session O/TUT)

TUT 4.2: Tutorium

Sonntag, 16. März 2025, 16:45–17:30, H10

Computing magnetic exchange interactions using DFT — •Manuel dos Santos Dias — Scientific Computing Department, STFC Daresbury Laboratory, United Kingdom

Magnetic materials are an unending source of fascinating physical behaviour which have fundamental appeal but also important technological applications. In order to understand, quantify and predict the properties of magnetic materials, we need information about the magnetic exchange interactions (introduced in the preceding tutorial), which control how the different magnetic atoms interact with each other and respond to external stimuli. This tutorial will give an overview on first-principles approaches to the calculation of magnetic exchange interactions using density functional theory (DFT). First I will outline how the properties of magnetic materials can be computed with and what capabilities are offered by different DFT codes. Next I will discuss how to map DFT calculations to spin models and when such a mapping is expected to work, followed by a discussion of the two main approaches to compute magnetic exchange interactions: the infinitesimal rotation method and the spin cluster expansion. Lastly, I will explain how to obtain simple information from the computed magnetic exchange interactions, such as the magnetic ground state and the spin wave spectrum, and how to connect to atomistic spin dynamics (for instance using the Spirit code covered in the next tutorial), Monte Carlo and micromagnetic simulations.

Keywords: exchange interactions; DFT; atomistic spin dynamics