Superconductivity with strong electron-phonon coupling in noncentrosymmetric W3Al2C

Abstract

We report the discovery of superconductivity in W3Al2C (Tc=7.6K) synthesized by high-pressure method. W3Al2C is isostructural to Mo3Al2C (space group P4132) but with stronger spin-orbit coupling (SOC). Different from the Mo3Al2C with metallic nature, the resistivity of the normal state of W3Al2C shows a nonmetallic behavior. A specific-heat jump of ΔCes/γTc=2.7 and gap energy of 2Δ(0)/γTc=5.43 are observed, which are much larger than that of Mo3Al2C (2.1 and 4.03) and the expectation of Bardeen-Cooper-Schrieffer theory (1.43 and 3.52). However, the Sommerfeld coefficient of W3Al2C is less than half of that of its Mo counterpart, and the specific heat above 2 K shows a power-law divergence following Ces/γTc∼(T/Tc)3.3 rather than an exponential relation. Theoretical calculations show that the Fermi surface of W3Al2C is dominated by W-5d electrons and the inclusion of SOC significantly changes its band structure, density of states, and Fermi surface topology. The realization of superconductivity by replacing 4d Mo toward 5dW provides a candidate for the search of potential triplet superconductors with enhanced SOC.

Source-reported materials — not catalogue approval

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