ABSTRACT
We report the synthesis, crystal structure, and physical properties of a novel ternary compound, Th2Cu4As5. The material crystallizes in a tetragonal structure with lattice parameters a = 4.0639(3) Å and c = 24.8221(17) Å. Its structure can be described as an alternating stacking of fluorite-type Th2As2 layers with antifluorite-type double-layered Cu4As3 slabs. The measurement of electrical resistivity, magnetic susceptibility, and specific heat reveals that Th2Cu4As5 undergoes bulk superconducting transition at 4.2 K. Additionally, all these physical quantities exhibit anomalies at 48 K, accompanied by a sign change in the Hall coefficient, suggesting a charge-density-wave-like (CDW) phase transition. Drawing from both experimental data and band calculations, we propose that the superconducting and CDW-like phase transitions are, respectively, associated with the Cu4As3 slabs and the As plane in the Th2As2 layers.
ABSTRACT
A quaternary compound with the composition Mo3ReRuC is obtained in a previously unexplored MoReRu-Mo2C system. According to X-ray structural analysis, Mo3ReRuC crystallizes in the noncentrosymmetric space group P4132 [cubic ß-Mn-type structure, a = 6.8107(1) Å]. Below 7.7 K, Mo3ReRuC becomes a bulk type-II superconductor with an upper critical field close to the Pauli paramagnetic limit. The specific heat data give a large normalized jump ΔCp/γTc = 2.3 at Tc, which points to a strongly coupled superconducting state. First-principles calculations show that its electronic states at the Fermi level are mainly contributed by Mo, Re, and Ru atoms and strongly increased by the spin-orbit coupling. Our finding suggests that the intermediate phase between alloys and carbides may be a good place to look for ß-Mn-type noncentrosymmetric superconductors.