Peculiarities of the Transport Properties of a Strongly Correlated Incommensurate Organic Superconductor κ-(BEDT-TTF) 4 Hg 2.89 Br 8

We present the results of measuring the dynamic magnetic susceptibility and surface impedance of a unique layered organic superconductor κ-(BEDT-TTF) 4 Hg 2.89 Br 8 (κ-HgBr). In this material, strong electronic correlations coexist with weak doping associated with lattice incommensurability. The superconducting properties of this material are studied by several methods: the temperature dependences of the resistance across the conducting layers, the dynamic magnetic susceptibility, and the surface impedance in the conducting planes are measured. The results of measuring the resistance and dynamic magnetic susceptibility at a frequency of 100 kHz demonstrated the presence of a superconducting state at temperatures below T c = 3.1 K. The results of measuring the temperature dependence of the surface impedance Z ( T ) = R ( T ) + iX ( T ) of several samples at a frequency of 28 GHz in the temperature range from 0.5 K to 50 K turned out to be unusual. In the studied samples at T < 3 K, a sharp change in Z ( T ) is not observed, and some samples even demonstrate weak “dielectricization” at low temperatures.