MagSAF: Software for simulating and fitting magnetic hysteresis loops of synthetic antiferromagnets

We have developed the macrospin-based software MagSAF that allows for fast and easy simulations of magnetic hysteresis loops of synthetic antiferromagnets with in-plane magnetization and in-plane uniaxial magnetic anisotropies. Additionally, the bilinear and biquadratic interlayer exchange coupling strengths can be extracted from experimental data via curve fitting. It also nurtures understanding the physics behind the magnetic hysteresis loops by allowing the user to examine the macrospin angle rotation and the energy landscape during the magnetic field sweep. We prepared CoFeB(5nm)/Ru(dRu)/CoFeB(5nm) synthetic antiferromagnets with 0.4nm≤dRu≤0.85nm to test our software. We find great agreement between our extracted bilinear and biquadratic coupling strengths and those that were obtained with a more advanced discrete energy model that takes the twisting of spins over the ferromagnetic layer thickness into account. For a thicker synthetic antiferromagnet CoFeB(18.0 nm)/Ru(0.55 nm)/CoFeB(5.75 nm), the differences between the macrospin and discrete energy model become more apparent.