Magnetotransport of Vertex Frustrated Artificial Spin Ice Structures

Artificial spin ice (ASI) systems are 2D analogues of pyrochlore spin ice, which exhibit frustrated magnetism and magnetic monopole-like defects [1]. ASI is commonly studied in honeycomb or square lattices, but other geometries which exhibit frustration are of growing interest. Previous magnetotransport studies have observed an asymmetric Hall signal and postulated this is related to the phase transition to the chirally ordered state in the kagome lattice [2]. Due to the possible effect of exchange bias [3] and the breakdown of the macrospin approximation for cobalt ASI systems below 50K [4] this has continued to be a topic of much interest and debate. The comparison of the response of different geometries could provide insight which could clarify the origin of this effect. Here we present an investigation of the Longitudinal and Hall resistivity, in the range 2K<T<290K, for non-conventional ASI geometries. Samples consist of permalloy nanowires in 5 geometries: kagome, square, Shakti, brickwork and tetris.

[1]: S. Ladak et al. New J. Phys. 13(5), 359 (2011)
[2]: W.R. Branford et al., Science 335(6076), 1597 (2012)
[3]: B.L. Le et al., New J. Phys. 17(2), 023047 (2015)
[4]: K. Zeissler et al., Sci. Rep., 630218 (2016)