Investigation of carrier transport properties along the c-axis in K0.8Fe2Se2 superconducting crystals

Abstract

We have successfully prepared the iron-based superconductor K0.8Fe2Se2 crystals (Tc=27 K) and studied the carrier transport properties along the c-axis in detail. Samples are characterized by XRD, SEM and temperature-dependent resistivity. The result shows that there is “phase separation” in the samples. Based on the experimental results, the iron-based superconductor is not a simple two phases alternating along the c-axis, but the metal phases should have weak-link channels along the c-axis, forming a nearly 3D special net mode. Studies of the thermal conductivity and the complex impedance spectrum z(omega, T0) suggest that the superconducting crystals have a lot of grain boundaries along the c-axis direction, the bound polarization charges result in relative dielectric constant of about 106 in magnitude and negative phase characteristics in the vicinity of 10 MHz.