Roman Kracht, PhD Student at ETH Zürich
The XY model describes interacting spins in the plane and captures the essence of the topological Berezinskii–Kosterlitz–Thouless (BKT) transition observed in systems such as superfluid helium or superconducting films. The vortex excitations that drive the BKT transition arise in a strictly two-dimensional setting, but real materials often consist of multiple weakly coupled layers, effectively extending the model to three dimensions. This stretches vortices into vortex loops and changes the topological transition into a standard second-order phase transition. We examine these effects using Monte Carlo simulations, which act like a “numerical microscope”, offering insights constrained only by computational and not by experimental boundaries. In this talk, I will introduce the Monte Carlo technique and show how we apply it to the three-dimensional XY model, focusing on how anisotropy alters its critical behavior.
Recording
There will be a live stream, but there will be *no* recording.