Figure 4. Effects of magnetic fields on the magnetic and superconducting transitions under high pressure.

(a–d, i–l) ρ(T) curves at different magnetic fields applied parallel to the c axis. The magnetic transition temperature T_m is field independent and marked by the green arrow (a–d). At 6.3 GPa, the T_m anomaly is only visible at high fields (i). (e–h, m–p) H-T phase diagrams. The zero resistivity is attained below T_c and the line (determined by the peak in dρ/dT(T)) is a lower bound of upper critical field H_c2. The sharp superconducting transitions under magnetic fields for P>6.3 GPa indicate narrowed regimes of the vortex liquid state.