Ground states and magnetization process for an triangular lattice array   of magnetic dots with perpendicular anisotropy
  We analyzed the ground state of the array of magnetic particles (magnetic dots) which form a two-dimensional triangular lattice, and magnetic moment of which is perpendicular to the plane of the lattice, in the presence of external magnetic field. In the small fields long range dipole-dipole interaction leads to the specific antiferromagnetic order, where two out of six nearest neighbors of the particle have the same direction of magnetization moment and four - the opposite one. It is shown that magnetization process in such array of particles as opposed to the rectangular lattices results from the formation of the magnetized topological defects (dislocations) in the shape of the domain walls. 
V. E. Kireev, R. S. Khymyn, B. A. Ivanov, C. E. Zaspel
cond-mat.mtrl-sci