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Portfolio of Ben Brown

Geometry and Spin Transport in Skyrmion Magnets

Researcher: Ben Brown
Supervised by: Dr. Gareth Alexander
Home department: Physics
Expected start date: 28/06/2016
Expected end date: 17/09/2016

About the Researcher


I am a Maths and Physics student on a Masters degree, going into my 4th Year in October 2016. My academic interests lie within differential geometry, symplectic topology, partial differential equations, and their applications within mathematical physics. Within the Physics department, I was on the Student Staff Liasion Committee for the first two years of my degree, in which I represented the views of the student body to the staff members.

About this Project

Magnetic skyrmions come about in chiral compounds as a result of two key interactions: the ferromagnetic interaction (which tries to align the spins of the atoms) and the Dzyaloshinskii-Moriya interaction (which only arises in chiral compounds). The ground-state of these two interactions results in a magnetic skyrmion, described a whirling magnetic structure (see Figure 1). They have attracted the attention of physicists and mathematicians alike since the structure cannot be deformed into a trivial state (i.e. one where all of the magnetisation vectors are aligned in one direction), which endows magnetic skyrmions with a form of stability through a topological quantum number.

A skyrmion configuration.

Figure 1: A skyrmion configuration, described by a magnetic whirl which admits a topological winding.

The aim of this project is to investigate the nature of the emergent electromagnetic fields that arise when an electron travels through a skyrmion texture. When said electron passes through the magnetic texture, its spin couples to the magnetisation and its wavefunction gains a Berry, or geometric, phase. Interestingly, this phase manifests itself physically in the form of an emergent magnetic field, which then influences the dynamics of the electron (see Figure 2). Furthermore if the skyrmion magnetic texture has a time-dependence then an additional electric field is given rise to, analogous to Faraday's law.


Figure 2: A cartoon demonstrating how the electron spin couples to the magnetisation of the skyrmion, resulting in a force acting upon it. This phenomenon is explained by emergent electromagnetic fields.

Project Files

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