PhD: Modelling Micromagnetism and Permanent Magnets

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Description of the offer :

A PhD fellowship on studying permanent magnets using a micromagnetism modeling framework is now available at the Department of Energy Conversion and Storage, Technical University of Denmark in collaboration with the Poul Due Jensen Foundation.

This PhD position at DTU Energy will constitute one part in a unique research project where we want to model permanent magnets on the microstructural level to understand why their resistance to opposing magnetic fields, their so-called coercivity, is much lower than theoretically predicted. The coercivity is the magnetic field that the permanent magnet can withstand before it flips and points in the opposite direction. We will study this phenomenon by realizing a novel and fast computational model built on an existing computational framework for magnetic field calculation written in Fortran.

For all known permanent magnet materials, the observed coercivity is at most 40% of the theoretical value. This discrepancy between the theoretical calculation of the coercive magnetic field and the observed coercive field of permanent magnets is known as Brown’s paradox. In this project, we will study this paradox for the most powerful permanent magnets available: NdFeB magnets. The goal of this project is to determine what physical mechanism causes Browns paradox. This will be done by realizing a new and much more powerful micromagnetism model by expanding our current mesoscale model for magnetism to include the physics needed for a micromagnetism model. Micromagnetic systems are governed by several interplaying physical mechanisms, namely exchange interaction, crystal anisotropy, Zeeman effect and macroscopic demagnetization. Once Browns paradox has been understood, the following logical step will be to propose a mechanism that alleviates the coercivity problem.

Your role as a PhD student will be to expand our magnetism model to a full dynamic micromagnetism model together with a post doc in the project. Once this is done, you will use the model to explore Brown’s paradox and the mechanisms reducing coercivity in permanent NdFeB magnets. We have a US partner in the project and as a PhD student you would spend about three to six months there to learn about micromagnetism and coercivity reducing phenomena.

At the end of the PhD project, we will have developed fully open source model framework for micromagnetic simulations and have investigated the coercivity reducing phenomena and thereby explained Brown’s paradox. The main activity will take place at the Department of Energy Conversion and Storage at DTU Risø campus initially and from ultimo 2019 at DTU Lyngby campus, as the department is being united at this campus.

See details and apply at https://www.dtu.dk/english/About/JOB-and-CAREER/vacant-positions/job?id=2ddbc9a5-b137-4571-96a9-342890575ed0

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