ANOMALOUS COERCIVITY IN HYSTERESIS LOOPS OF ANTIFERROMAGNETICALLY COUPLED FE AG/FE TRILAYERS ON MGO(001) SUBSTRATES/

A numerical simulation of the demagnetization process (hysteresis loop ) is performed in order to evaluate the bilinear and biquadratic coupl ing in the MgO/[Fe/Ag/Fe]/Ag trilayer. The proposed approach is interm ediate between the model assuming that the system always reaches the G lobal Energy Minimum (GEM) and the model considering the situation whe n the system follows the Local Energy Minimum (LEM). The intermediate approach is realized by defining the energy barrier parameter E-b dete rmining the transition between the local energy minima. The value of E -b can be obtained using reference (uncoupled) samples. The numerical algorithm applied to the GEM, LEM and the intermediate model is descri bed. The bilinear J(1) and biquadratic J(2) coupling parameters are de termined from the ferromagnetic resonance and hysteresis loop measurem ents.