McPhase model calculations of the magnetic phase diagram of CeCu2Ge2 - Prediction of a double q magnetic structure

The magnetic (H,T)-phase diagram of CeCu2Ge2 has been studied by model calculations using the McPhase program. Aiming at the best possible description of the magnetic properties model parameters were varied and the complexity of the model approach was increased. A double-q magnetic structure was predicted with q+ = (hhl) and q- = (h-hl) that changes to a single-q one at applied in plane magnetic field. The extent and stability of the double-q magnetic structure was investigated and physical properties are compared to available experimental data. The calculations reveal the principal shape of magnetisation curves and the calculated (H,T)-phase diagram agrees satisfactorily to that deduced from experiments. The consistence of experimental results and theoretical model is important for the understanding of magnetism in CeCu2Ge2 and the heavy fermion superconductor CeCu2Si2.