The superconductivity in Re-B system

We present here the low temperature electrical transport and magnetic properties of intermetallic rhenium boride compounds. We newly discovered the superconductivity of Re₇B₃ (T_c = 3.3 K) and its superconducting properties were discussed. We also discussed the physical properties of Re₃B (T_c = 4.8 K), of which superconductivity was discussed by Strukova et al. The crystal structures of these compounds (Re₃B and Re₇B₃) are orthorhombic (space group Cmcm) and hexagonal (P6₃/mc), respectively, and have different B-B bonds each other. The magnetization (M-H) curves of these compounds show a typical type-II superconducting behavior. The lower critical field, H_c1(0), the upper critical field, H_c2(0) and the Ginzburg-Landau (GL) parameter, κ are, 8 mT, 5.2 T and 35 for Re₃B and 6mT, 0.9 T and 17 for Re₇B₃.