Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 23: Micro- and Nanostructured Magnetic Materials
MA 23.8: Vortrag
Mittwoch, 2. April 2014, 11:30–11:45, HSZ 403
Thermal excitations of artificial spin ice in square-lattice dipolar arrays — •Danny Thonig1,2, Stephan Reißaus2, and Jürgen Henk2 — 1Max Planck Institute of Microstructure Physics, Halle, Germany — 2Martin Luther University Halle-Wittenberg, Halle, Germany
Frustration in magnetic systems is a topic of particular interest in condensed matter physics. Recent experiments on artificial two-dimensional spin ice reveal thermal magnetic excitations, reminiscent of Dirac strings and magnetic monopoles [1]. We report on a theoretical investigation of artificial spin ice in square-lattice dipolar arrays, using a geometry adopted from recent experiments [2], applying conventional and kinetic Monte Carlo methods.
The number of thermal string excitations with quasi-monopoles ± 4 can be drastically increased by a vertical displacement, a change of the island’s thickness and variation of the magnetization of rows and columns. The increase is especially large at low temperatures. Addressing the thermal stability of these excitations, we provide time scales for their experimental observation. Furthermore, the excitations can be pinned by defects, which allows to control position and length of the string excitations.
[1] E. Mengotti et al., Nature Phys. 7 (2011) 68-74
[2] A. Farhan et al., Nature Phys. 9 (2013) 375.