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MA: Fachverband Magnetismus

MA 4: Micro- and Nanostructured Materials

MA 4.7: Talk

Monday, March 16, 2015, 11:15–11:30, H 1012

Building Blocks of Artificial Square Spin Ice: Stray-Field Studies of Thermal Dynamics and Tuned Interactions. — •Merlin Pohlit, Fabrizio Porrati, Michael Huth, and Jens Müller — Physikalisches Institut Goethe-University, Frankfurt a. M., Germany

Over the last decade, spin ice systems with their intricate interplay between disorder, frustration and degeneracy giving rise to fundamentally new phenomena like the occurrence of monopole excitations, came to the fore of intensive research interest. Due to the ability to tune the geometric shape and the possibility to access spatially-resolved magnetic properties, artificial spin ice systems, i.e. nanostructured arrays of macroscopic spins, were succesfully employed as 2D model systems for their 3D equivalent. Here we present magnetic measurements performed on individual building blocks of artificial square spin ice. For this purpose a thermally-active cobalt-based spin ice structure was grown by focused electron beam induced deposition (FEBID) onto the surface of a lithographically defined µm-sized Hall-sensor based on a two-dimensional electron gas of an AlGaAs/GaAs heterostructure. This setup provides continuous access to the array’s stray field during magnetization reversal. Using relatively simple temperature and magnetic field protocols, individual microstates were prepared and thermally-activated switching was observed. We demonstrate the feasibility of tuning the inter-macrospin interactions in artificial spin ice systems by additional deposition steps and electron irradiation at the lattice nodes.