Emergence of shallow energy levels in B-doped Q-carbon: A high-temperature superconductor
Emergence of shallow energy levels in B-doped Q-carbon: A high-temperature superconductor
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DOI：
10.1016/j.actamat.2019.05.013
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发表时间：
2019-08-01
期刊：
影响因子：
9.4
通讯作者：
Narayan, Jagdish
中科院分区：
文献类型：
--
作者：
Sachan, Ritesh;Hachtel, Jordan A.;Narayan, Jagdish
我们报道了在最近发现的硼掺杂Q -碳巴丁 - 库珀 - 施里弗（BCS）高温超导体中浅能级态的光谱学证明。Q -碳是通过超快熔化和淬火合成的，能够实现高硼掺杂浓度，这使得超导转变温度（$T_c$）提高到36 K（相比之下，硼掺杂金刚石为4 K）。$T_c$的提高归因于硼掺杂Q -碳中费米能级附近态密度的增加，这在$T_c$以下通过强电子 - 声子耦合产生超导态。然而，由于空间和能量分辨率有限，这些浅能级态很难绘制出来。在这里，我们使用超高能量分辨率的单色化电子能量损失光谱（EELS）来检测和可视化硼掺杂Q -碳费米能级附近（30 - 100 meV范围）新形成的浅能级态（振动模式）。通过这项研究，我们确立了高分辨率EELS在理解BCS超导碳基材料超导行为方面的重要性，这些材料在浅能级态存在的情况下表现出显著的增强。（C）2019由爱思唯尔有限公司代表Acta Materialia公司出版
We report the spectroscopic demonstration of the shallow-level energy states in the recently discovered B-doped Q-carbon Bardeen-Cooper-Schrieffer (BCS) high-temperature superconductor. The Q-carbon is synthesized by ultrafast melting and quenching, allowing for high B-doping concentrations which increase the superconducting transition temperature (T-c) to 36 K (compared to 4 K for B-doped diamond). The increase in T-c is attributed to the increased density of energy states near the Fermi level in B-doped Q-carbon, which give rise to superconducting states via strong electron-phonon coupling below T-c. These shallow-level energy states, however, are challenging to map due to limited spatial and energy resolution. Here, we use ultrahigh energy resolution monochromated electron energy-loss spectroscopy (EELS), to detect and visualize the newly formed shallow-level energy states (vibrational modes) near the Fermi level (ranging 30-100 meV) of the B-doped Q-carbon. With this study, we establish the significance of high-resolution EELS in understanding the superconducting behavior of BCS superconducting C-based materials, which demonstrate a phenomenal enhancement in the presence of shallow-level energy states. (C) 2019 Published by Elsevier Ltd on behalf of Acta Materialia Inc.