Materials Colloquium 2020 - April, 22nd, 16:30
Sandra Skjærvø (Mesoscopic Systems)
Artificial spin systems are arrays of nanomagnets that are fabricated through state-of-the-art lithography techniques. The nanomagnets interact through dipolar coupling and, depending on the arrangement of the nanomagnets, the system can order magnetically. With X-ray Photon Correlation Spectroscopy, we aim to understand the evolution of the magnetic order in an artificial spin system with square geometry through the known antiferromagnetic phase transition. Below the phase transition at TN, the system is in a single-domain antiferromagnetic ground state. Upon heating, slow fluctuations in the system lead to striking speckle patterns with distinct features and long life times. The small size and rectangular shape of the array of nanomagnets provides a possible explanation for the distinctness of the speckle patterns, with stripe-like domains nucleating at and propagating from the edges of the array, in line with previous observations.