Real-Space Dynamics via Increased Effective Dimension in Artificial Spin Glass

From ordering piles of sand [1] to comprehending the human mind [2], spin glass systems continue to inspire theorists and experimentalists alike. Artificial nanomagnet fabrication [3] offers a unique opportunity to directly visualize the dynamics of glassy systems. However, spin glass phases have only been discovered at finite temperature in systems embedded in dimensions greater than or equal to 3 [1,4]. In this study we fabricate Nanomagnet arrays such that the network of their interactions possesses an effective dimension [5] higher than 2. Dubbed the Bethe glass, this is first finite temperature spin glass embedded in two dimensions. Using XMCD [6] the time scale free relaxation of magnetic moments is filmed in real space, directly observing the supermetric qualities of [1] spin glass. Further, the effective dimension is varied to show the tunability of glass properties.

[1] Berthier, L., and G. Biroli. Rev. Mod. Phys. 83.2 (2011): 587.
[2] Hudetz, A. G., C. J. Humphries, and Jeffrey R. Binder. Front. Syst.Neurosci. 8 (2014): 234.
[3] Nisoli, C., R. Moessner, and P. Schiffer. Rev. Mod. Phys. 85.4 (2013): 1473.
[4] Hartmann, A. K., and A. P. Young. PRB 64.18 (2001): 180404.
[5] Daqing, L., et al. Nat. Phys. 7.6 (2011): 481.
[6] Stohr, J., et al. Science (1993): 658-661.