Fig. 2
From: Evidence of spontaneous vortex ground state in an iron-based ferromagnetic superconductor
Characteristic of the ferromagnetic superconductor Eu(Fe0.91Rh0.09)2As2 in relation with a spontaneous vortex phase. a The crystal and magnetic structure. b The superconducting resistive transition at T sc, followed by a resistivity revival below T m (note the logarithmic scale for resistivity). c Schematic H − T diagram showing the internal field H int (solid blue line), in comparison with the hypothetical irreversible field \(H_{{\rm{irr}}}^*\) (assuming H int = 0) as well as the hypothetical lower and upper critical fields, \(H_{{\rm{c1}}}^*\) and \(H_{{\rm{c2}}}^*\). SV and M denote the spontaneous-vortex phase and the Meissner state, respectively. d Temperature dependence of the dc magnetic susceptibility measured while heating up, with both field-cooled (FC) and zero-field-cooled (ZFC) histories. The demagnetization effect has been taken into account
