Magnetic functional materials - Magnetische Funktionsmaterialien_SS 2025

Why is iron ferromagnetic? How does a magnetic shape memory alloy work? What is a magnetocaloric material and why do we want to make a refrigerator out of it? What physical effect is important in permanent magnets? And how can we calculate it all?

This course introduces the physics behind modern functional magnetic materials used for energy conversion. We provide an overview of the basic models and theories describing metallic materials and explain their functional properties from the point of view of their smallest units, the electrons.

Functional  Magnetic Materials - from Itinerant Electrons to Modern Materials

Language: English or German, on mutual agreement between the participants

VO, 2 SWS
Mo 10 - 12, MD 468
(1. - 2. FS, WP) Ph M.Sc.

PJ, 2 SWS
Mi 14 - 16, MC 231
(1. - 2. FS, WP) Ph M.Sc.

Learning outcomes: 

Basic understanding of itinerant magnetism and the interplay between electronic properties and lattice structure using up-to-date examples

Topics:

• Quantum mechanical origin of magnetism, exchange interaction
• Elementary models of band magnetism: electron gas, Stoner model
• Thermodynamic properties and susceptibility. Metamagnetism
• Magnetism and lattice structure: iron as a prototype of a magnetic functional material.
• Magnetism and band filling: Slater-Pauling curve, semi-metallicity and shape memory effect in Heusler alloys
• Magnetism at finite temperatures: Itinerant vs. localized descriptions: Heisenberg model
• Realistic densities of states and numerical calculation methods
• Spin-orbit interaction: magnetocrystalline anisotropy and anisotropy of orbital moments. Hard magnetic materials (FePt, CoPt) in the bulk and on the nanometer scale.

Literature:

• Peter Mohn, Magnetism in the Solid State (Springer, 2005)
• Jürgen Kübler, Theory of Itinerant Electron Magnetism (Clarendon, 2000)
• A. M. Tishin, Y. I. Spichkin, The magnetocaloric Effekt and its Applications (IOP, 2003)
• R. Skomski, J.M.D. Coey, Permanent Magnetism (IOP, 1999)
• Richard M. Martin, Electronic Structure (Cambridge, 2004)
• J. Grotendorst, S. Blügel, D. Marx, Computational Nanoscience: Do It Yourself (NIC Series Vol. 31, Jülich 2006)