Regensburg 2019 – scientific programme

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MA: Fachverband Magnetismus

MA 55: Electron theory and micromagnetism

MA 55.14: Talk

Friday, April 5, 2019, 13:00–13:15, H38

Novel magnetic states in nano clusters — •Robert Baldock and Nicola Marzari — Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

We predict that very small clusters of ferromagnetic spins may exhibit stable magnetic states with fractional overall magnetisation in two and three dimensions. These ultra small systems, which are dominated by finite size effects, do not conform to mean field models of the magnetization. Instead, exotic magnetisation field temperature phase diagrams are observed, where discrete fractional magnetisations are stabilised at finite fields and temperatures.

We study these systems using advanced free energy methods, including nested sampling, which enable us to directly obtain magnetisation-temperature free energy surfaces, from which the magnetisation field temperature phase diagrams can be computed directly.