Influence of pressure on the properties of the multigap type-I superconductor BeAu

Abstract

We report on studies of the superconducting and normal-state properties of the noncentrosymmetric superconductor BeAu under hydrostatic pressure conditions. The room-temperature equation of state (EOS) reveals the values of the bulk modulus (B0) and its first derivative (B0′) at ambient pressure to be B0≃133GPa and B0′≃30, respectively. Up to the highest pressures studied (p≃2.2GPa), BeAu remains a multigap type-I superconductor. The analysis of Bc(T,p) data within the self-consistent two-gap approach suggests the presence of two superconducting energy gaps, with the gap-to-Tc ratios Δ1/kBTc∼2.3 and Δ2/kBTc∼1.1 for the larger and smaller gaps, respectively [Δ=Δ(0) is the zero-temperature value of the gap and kB is the Boltzmann constant]. With increasing pressure, Δ1/kBTc increases while Δ2/kBTc decreases, suggesting that pressure enhances (weakens) the coupling strength between the superconducting carriers within the bands where the larger (smaller) superconducting energy gap has opened. The superconducting transition temperature Tc, the zero-temperature values of the superconducting gaps Δ1 and Δ2, and the zero-temperature value of the thermodynamic critical field Bc(0) decrease with increasing pressure, with the rates of dTc/dp≃−0.197K/GPa, dΔ1/dp≃−0.034meV/GPa, dΔ2/dp≃−0.029meV/GPa, and dBc(0)/dp≃−2.65mT/GPa, respectively. The measured Bc(0) values plotted as a function of Tc follow an empirical scaling relation established for conventional type-I superconductors.

Source-reported materials — not catalogue approval

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