Ignoring your neighbors: Moment correlations dominated by indirect or   distant interactions in an ordered nanomagnet array
  We have studied the moment correlations within triangular lattice arrays of single-domain co-aligned nanoscale ferromagnetic islands. Independent variation of lattice spacing along and perpendicular to the island axis tunes the magnetostatic interactions between islands through a broad range of relative strengths. For certain lattice parameters, the sign of the correlations between near-neighbor island moments is opposite to that favored by the pair-wise interaction. This finding, supported by analysis of the total correlation in terms of direct and convoluted indirect contributions across multiple pairwise interactions, indicates that indirect interactions and/or those mediated by further neighbors can be tuned to be dominant, with implications for the wide range of systems composed of interacting nanomagnets. 
Sheng Zhang, Jie Li, Jason Bartell, Xianglin Ke, Cristiano Nisoli,   Paul E. Lammert, Vincent H. Crespi, and Peter Schiffer
cond-mat.mes-hall