  The magnetic orientations and switching fields of a CoCrPt-Ru-CoCrPt
synthetic ferrimagnet with perpendicular magnetic anisotropy have been studied
in the temperature range from 2 K to 300 K. It was found that two sets of
magnetic transitions occur in the CoCrPt-Ru-CoCrPt ferrimagnet across this
temperature range. The first set exhibits three magnetic transitions in the 50
K - 370 K range, whereas the second involves only two transitions in the 2 K
and 50 K range. The observed magnetic hysteresis curves of the synthetic
ferrimagnet are explained using the energy diagram technique framework
pioneered by Koplak et al. [1] which accurately describes the competition
between interlayer exchange coupling energy, Zeeman energy, and anisotropy
energy in the system. In this work we expand the framework to include synthetic
ferrimagnets (SFMs) comprising higher perpendicular magnetic anisotropy
materials and large (4X) interlayer exchange coupling energies which are
promising for the development of ultrafast (ps) magnetic switching free layers
in MTJ structures. Furthermore, we apply the analysis to predict SFM magnetic
hysteresis curves in a temperature regime that includes temperature extrema
that a synthetic ferrimagnet would be expected to reliably operate at, were it
to be utilized as a free layer in a memory or sensor spintronic device.

Materials Science