Fingerprints of Universal Spin-Stiffness Jump in Two-Dimensional Ferromagnets

Motivated by recent progress on synthesizing two-dimensional magnetic van der Waals systems, I will talk about a proposal for detecting the topological Berezinskii-Kosterlitz-Thouless (BKT) phase transition in spin-transport experiments. Here we demonstrate that the spatial correlations of injected spin-currents into a pair of metallic leads can be used to measure the predicted universal jump of 2/π in the ferromagnet spin-stiffness. Our setup provides a simple route to measuring this (up to now elusive) topological phase transition in two-dimensional magnetic systems. It is hoped that this will encourage experimental efforts to investigate critical phenomena beyond the standard Ginzburg-Landau paradigm in low-dimensional magnetic systems with no local order parameter.