Figure 3: Detailed phase diagram of Ba1−xKxFe2As2.
From: Superconductivity-induced re-entrance of the orthorhombic distortion in Ba1−xKxFe2As2
(a) Phase diagram of Ba1−xKxFe2As2 spanning the whole substition range. Ts,N, T1, T2 and Tc (determined from the data shown in Fig. 2 and additional thermodynamic data) are shown by symbols. Lines and coloured areas are a guide to the eye indicating the five distinct thermodynamically ordered phases. A narrow region of a C4-symmetric (tetragonal) magnetic phase, occurring within the usual C2-symmetric (orthorhombic) SDW phase, is observed. It coexists with superconductivity with a reduced Tc. Superconductivity-induced reentrance of the C2-SDW phase occurs at T2. The inset shows an enlarged view of the region containing the C4-magnetic phase. Vertical error bars indicate the uncertainty in the transition temperatures and horizontal error bars indicate the statistical error in the sample composition. (b) Predicted effect of uniaxial in-plane pressure pab on the phase diagram, from thermodynamic relations using our thermal-expansion and heat-capacity data. The direction of the arrows indicates the sign of the pressure derivative of the transition temperature and the length is proportional to its absolute value (see scale). Lines are reproduced from panel (a).
