Topological phases and phase transitions in magnets and ice

Keesman, R. (2017)

Doctoral Thesis

The main focus of this Thesis is the behaviour of two-dimensional materials,
namely (anti)-ferromagnetic materials in the first two chapters, which show
topological phases, and energetic square ice in the third and fourth chapter.
The magnetic materials are of interest in part due to foreseen practical applications
in which skyrmions can act as data carriers for which we have shown
that skyrmions can exist in the ground state. Energetic square ice is of theoretical
interest due to its anomalous behaviour at the infinite-order phase
transition and as a purely mathematical analytically solvable model. We used
this model to test the order parameter we constructed that, by definition, can
be used to detect these infinite-order phase transitions. We also show agreement
between conjectured and known properties for energetic square ice
with special boundaries and show the existence of oscillations that go beyond
current theories.

• Monte-Carlo
• simulation
• phase-transition
• F-model
• skyrmions

• All authors: Keesman, R.
• Supervisor: Barkema, G.T.; Duijne, R.A.
• Committee: Fritz, L.; Mostovoy, M.V.; Aarts, J.; Eliel, E.R.
• Qualification: Doctor (dr.)
• Awarding Institution: Lorentz Institute for theoretical physics, Faculty of Sciences, Leiden University
• Date: 2017-06-07
• Title of host publication: Casimir PhD Series
• ISBN (print): 9789085932970
• Name: 2017-14