Fig. 3

Nickelate phase diagram. Phase diagram of RNiO₃ compounds in terms of their tolerance factor t and the temperature T. It includes three phases: a metallic Pbnm paramagnetic phase (PM-M, yellow area); an insulating P2₁/n paramagnetic phase (PM-I, green area); and an insulating P2₁/n E′-type AFM phase (AFM-I, magenta area). The yellow line and dots show the experimental evolution of T _MI with the tolerance factor t. The blue line and squares is the prediction of the simple Landau model fitted on the first-principles data (FM order). The dashed blue line is the fit of the Landau expression of T _MI (t) on experimental data. The blue star is the magnetic phase transition predicted for YNiO₃ from first principles. The blue arrows indicate the correction to be applied on T _MI for large cations when properly incorporating the change of magnetic order