Nuanced superconductivity in endohedral gallide Mo8Ga41

Abstract

We report on synthesis and characterization of gallide cluster based Mo8Ga41 superconductor. Transport and magnetization measurements confirm the superconducting transition temperature to be 9.8 K. The upper critical field (Hc2), lower critical field (Hc1), Ginzburg-Landau coherence length ( ξ GL) and penetration depth(λ) are estimated to be 11.8 T, 150 G, 5.28 nm, 148 nm respectively. The electronic band structure, density of states and phonon dispersion curve calculations are obtained by using Density Functional Theory. The core level x-ray Photoelectron Spectroscopy (XPS) reveals the binding energy information of the constituting elements Mo and Ga in Mo8Ga41. The valence band spectra from XPS are in good agreement with calculated density of states (DOS). The zero field critical current density (Jc) at T = 2 K is ∼3 × 105 A/cm2 which is indicative of efficient flux pinning in the as grown compound. About two fold enhancement in critical current density with application of external pressure (1.1 GPa) is observed with marginal decrease in transition temperature. The fitting of current density to double exponential model confirms possibility of two gap superconductivity in Mo8Ga41.