Superconductivity in SrB3C3 clathrate

We predict superconductivity for the carbon-boron clathrate SrB3C3 with Tc = 27-43 K for Coulomb pseudopotential (mu*) values between 0.17 and 0.10 using first-principles calculations with conventional electron- phonon coupling. Electrical transport measurements, facilitated by an in situ experimental design compatible with extreme synthesis conditions (> 3000 K at 50 GPa), show nonhysteretic resistivity drops that track the calculated magnitude and pressure dependence of superconductivity for mu* approximate to 0.15, and transport measurements collected under applied magnetic fields indicate superconductivity with an onset Tc of approximately 20 K at 40 GPa. Carbon-based clathrates thus represent a class of superconductors similar to other covalent metals like MgB2 and doped fullerenes. Carbon clathrates share structures similar to superconducting superhydrides with wide potential for tunable properties, and covalent C-B bonds allow metastable persistence at ambient conditions.

Automated summary

We predict superconductivity in the carbon-boron clathrate SrB3C3 with a critical temperature (Tc) range of 27-43 K for certain Coulomb pseudopotential (mu*) values (0.17-0.10). Experimental measurements of electrical transport under extreme synthesis conditions (>3000 K at 50 GPa) show resistivity drops consistent with the calculated magnitude and pressure dependence of superconductivity for mu* approximately 0.15, and magnetic field measurements indicate an onset Tc of approximately 20 K at 40 GPa. Carbon-based clathrates present a new class of superconductors with potential tunable properties and metastable persistence at ambient conditions, similar to other covalent metals and doped fullerenes.