Universiteit Leiden

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Topological phases and phase transitions in magnets and ice

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.

R. Keesman
07 juni 2017
Thesis in Leiden Repository

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.