Figure 2

Temperature dependence of the longitudinal resistance \(R_{ab}\) of the Ba\(_{0.6}\)K\(_{0.4}\)(FeAs)\(_2\) single crystal in the temperature range \((4.2 \div 280)\, {\mathrm {K}}\). The inset shows the temperature dependence of the magnetic susceptibility of this sample under cooling in zero magnetic field. \(R(300 \, {\mathrm {K}})/R(40 \, {\mathrm {K}}) = 12\), \(T_c = 38.5 \, {\mathrm {K}}\), \(\Delta T_c (10\% \div 90\%) = 0.3 \, {\mathrm {K}}\) as determined from the magnetic susceptibility.