Quantitative Decoding of Interactions in Tunable Nanomagnet Arrays Using   First Order Reversal Curves
  To develop a full understanding of interactions in nanomagnet arrays is a persistent challenge, critically impacting their technological acceptance. This paper reports the experimental, numerical and analytical investigation of interactions in arrays of Co nanoellipses using the first-order reversal curve (FORC) technique. A mean-field analysis has revealed the physical mechanisms giving rise to all of the observed features: a shift of the non-interacting FORC-ridge at the low-H$_c$ end off the local coercivity H$_c$ axis; a stretch of the FORC-ridge at the high-H$_c$ end without shifting it off the H$_c$ axis; and a formation of a tilted edge connected to the ridge at the low-H$_c$ end. Changing from flat to Gaussian coercivity distribution produces a negative feature, bends the ridge, and broadens the edge. Finally, nearest neighbor interactions segment the FORC-ridge. These results demonstrate that the FORC approach provides a comprehensive framework to qualitatively and quantitatively decode interactions in nanomagnet arrays. 
Dustin A. Gilbert, Gergely T. Zimanyi, Randy K. Dumas, Michael   Winklhofer, Alicia Gomez, Nasim Eibagi, J. L.Vicent, and Ka...
cond-mat.mtrl-sci cond-mat.mes-hall