Magnetic phase diagram of two identical coupled nanomagnets

The theoretical magnetic phase diagram of two identical nanomagnets is presented. The nanomagnets are assumed to be single domains in the shape of very flat ellipsoids, in order to approximate technologically relevant thin-film samples patterned into ellipses. The phase diagram is organized by type of easy axis hysteresis loop and takes into account, using exact closed analytic expressions, the effect of thickness, width, length, magnetization, and uniaxial intrinsic anisotropy of the two nanoparticles, and exchange coupling between the two particles. Two phase diagrams are presented for the two cases where the intrinsic anisotropy is parallel to either the long or short in-plane axis of the nanoparticles. Complete descriptions of all hysteresis loops and exact analytic formulas for all switching fields are given. (C) 2004 American Institute of Physics.