Magnetic hysteresis of an artificial square ice studied by in-plane Bragg x-ray resonant magnetic scattering

• Main Authors: J. P. Morgan, C. J. Kinane, T. R. Charlton, A. Stein, C. Sánchez-Hanke, D. A. Arena, S. Langridge, C. H. Marrows
• Format: Article
• Language: English
• Published: AIP Publishing LLC 2012-06-01
• Series: AIP Advances
• Online Access: http://dx.doi.org/10.1063/1.4732147

We report X-ray resonant magnetic scattering studies of a Permalloy artificial square ice nanomagnet array, focussing on the field-driven evolution of the sum Σ and difference Δ signals of left and right handed circularly polarized synchrotron X-rays at different lateral positions in reciprocal space Qx. We used X-rays tuned to the Fe L3 resonance energy, with the scattering plane aligned along a principal symmetry axis of the array. Details of the specular Δ hysteresis curve are discussed, following the system magnetization from an initial demagnetized state. The periodic structure gives rise to distinct peaks at in-plane reciprocal Bragg positions, as shown by fitting Σ(Qx) to a model based on a simple unit cell structure. Diffraction order-dependent hysteresis in Δ is observed, indicative of the reordering of magnetization on the system's two interpenetrating sublattices, which markedly deviates from an ideal Ising picture under strong applied fields.