Thermally and field-driven mobility of emergent magnetic charges in square artificial spin ice

Sophie A. Morley; Jose Maria Porro; Aleš Hrabec; Mark C. Rosamond; Edmund H. Linfield; Gavin Burnell; Mi-Young Im; Peter J. Fischer; Sean Langridge; Christopher H. Marrows

doi:10.1038/s41598-019-52460-7

arXiv · 1809.07472

Thermally and field-driven mobility of emergent magnetic charges in square artificial spin ice

Sophie A. Morley·Jose Maria Porro·Aleš Hrabec·Mark C. Rosamond·Edmund H. Linfield·Gavin Burnell·Mi-Young Im·Peter J. Fischer·Sean Langridge·Christopher H. Marrows

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Abstract

Designing and constructing model systems that embody the statistical mechanics of frustration is now possible using nanotechnology. We have arranged nanomagnets on a two-dimensional square lattice to form an artificial spin ice, and studied its fractional excitations, emergent magnetic monopoles, and how they respond to a driving field using X-ray magnetic microscopy. We observe a regime in which the monopole drift velocity is linear in field above a critical field for the onset of motion. The temperature dependence of the critical field can be described by introducing an interaction term into the Bean-Livingston model of field-assisted barrier hopping. By analogy with electrical charge drift motion, we define and measure a monopole mobility that is larger both for higher temperatures and stronger interactions between nanomagnets. The mobility in this linear regime is described by a creep model of zero-dimensional charges moving within a network of quasi-one-dimensional objects.

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Sophie A. Morley, Jose Maria Porro, Aleš Hrabec, Mark C. Rosamond, Edmund H. Linfield, Gavin Burnell, Mi-Young Im, Peter J. Fischer, Sean Langridge, Christopher H. Marrows. 2018-09-20. Thermally and field-driven mobility of emergent magnetic charges in square artificial spin ice. https://doi.org/10.1038/s41598-019-52460-7

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