Fig. 4
From: Unique defect structure and advantageous vortex pinning properties in superconducting CaKFe4As4
Vortex phase diagrams under H // c for a CaK1144 and b BaK122 (x = 0.3). H and T dependences of Jc are shown in the form of contour plots. Hot (cold) colours indicate high (low) Jc region. Several characteristic T and H are plotted: Ton, the onset of the peak effect in Jc–T curves defined by the local minimum (purple squares); Tp, the peak position in Jc–T (blue diamonds); Hon, the onset of the second magnetization peak in M–H curves defined by the local minimum (open reversed triangles); Hp, the second peak position in M–H (open triangles); Hirr, irreversibility field defined by a criterion of Jc < 100 A/cm2 (open circles); and Hc2, the upper critical field along the c axis obtained from the resistivity measurements (orange circles). The dashed lines are guide for the eye
