Ritesh Sachan1 2 Anagh Bhaumik2 Siddarth Gupta2 Jagdish Narayan2

1, Army Research Office, Research Triangle Park, North Carolina, United States
2, North Carolina State University, Raleigh, North Carolina, United States

We report high-temperature superconductivity in B-doped amorphous quenched carbon (Q-carbon). This phase is formed after nanosecond laser melting of B-doped amorphous carbon films in a super undercooled state and followed by rapid quenching. Magnetic susceptibility measurements show the characteristics of type-II Bardeen-Cooper-Schrieffer superconductivity with a superconducting transition temperature (Tc) of 36.0±0.5 K for 17.0±1.0 atomic percent boron concentration. This value is significantly higher than the best experimentally reported Tc of 11 K for crystalline B-doped diamond. We argue that the quenching from metallic carbon liquid leads to a stronger electron-phonon coupling due to close packing of carbon atoms with higher density of states at the Fermi level. With these results, we propose that the non-equilibrium undercooling assisted synthesis method can be used to fabricate highly doped materials which provide greatly enhanced superconducting properties.
[1] Bhaumik, A; Sachan, R; Narayan, J. High-Temperature Superconductivity in Boron-Doped Q-Carbon. ACS Nano 2017, DOI: 10.1021/acsnano.7b01294.