Department of Materials Science and Engineering, North Carolina State University, Centennial Campus , Raleigh, North Carolina 27695-7907, United States.
Materials Science Division, Army Research Office , Research Triangle Park, Durham, North Carolina 27709, United States.
ACS Nano. 2017 Dec 26;11(12):11915-11922. doi: 10.1021/acsnano.7b06888. Epub 2017 Nov 10.
We have achieved a superconducting transition temperature (T) of 55 K in 27 at% B-doped Q-carbon. This value represents a significant improvement over previously reported T of 36 K in B-doped Q-carbon and is the highest T for conventional BCS (Bardeen-Cooper-Schrieffer) superconductivity in bulk carbon-based materials. The B-doped Q-carbon exhibits type-II superconducting characteristics with H(0) ∼ 10.4 T, consistent with the BCS formalism. The B-doped Q-carbon is formed by nanosecond laser melting of B/C multilayered films in a super undercooled state and subsequent quenching. It is determined that ∼67% of the total boron exists with carbon in a sp hybridized state, which is responsible for the substantially enhanced T. Through the study of the vibrational modes, we deduce that higher density of states near the Fermi level and moderate to strong electron-phonon coupling lead to a high T of 55 K. With these results, we establish that heavy B doping in Q-carbon is the pathway for achieving high-temperature superconductivity.
我们在 27at% B 掺杂 Q-碳中实现了 55K 的超导转变温度（T）。这一数值相较于之前报道的 36K 有显著提升，是在块状碳基材料中实现的常规 BCS（Bardeen-Cooper-Schrieffer）超导电性的最高 T 值。B 掺杂 Q-碳表现出 II 型超导特性，H(0) ∼ 10.4T，与 BCS 公式一致。B 掺杂 Q-碳是通过在过冷状态下纳秒激光熔解 B/C 多层膜，并随后淬火形成的。确定约 67%的总硼与碳以 sp 杂化态存在，这是 T 值显著增强的原因。通过对振动模式的研究，我们推断出费米能级附近较高的态密度和适中到较强的电子-声子耦合导致了 55K 的高 T 值。有了这些结果，我们确定了 Q-碳中重 B 掺杂是实现高温超导的途径。
