发表机构
Robinson Research Institute, Victoria University of Wellington（惠灵顿维多利亚大学罗宾逊研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该评论指出四层铜酸盐CuC-1234的双超导能隙行为符合Tc与键价和参数V+的长期相关性，OP的Tc2由其局部结构决定，体现了极短程物理特性。
AI 中文摘要
在最近的一篇快报中，Sun等人报道了对四层铜酸盐(Cu,C)Ba₂Ca₃Cu₄O₁₁（CuC-1234）的光电子能谱测量，他们在该样品中分辨出与内部（IP）和外部（OP）CuO₂平面对应的两个超导能隙。该样品的Tc为117 K，此前已通过中子粉末衍射对其结构进行了表征。从Luttinger求和可知，IP的β带处于严重欠掺杂状态（p≈0.07），而OP的α2成键带处于强过掺杂状态（p≈0.25）。每个带均显示出具有截然不同动量和温度依赖关系的能隙：β带上的大能隙在体Tc处闭合，而α2带上的小能隙在70 K处闭合。这种双能隙行为表明IP与OP之间存在弱耦合，从而导致出现第二个能隙打开温度Tc2，意味着超流密度在冷却过程中会分两步发展，首先在IP上，随后在OP上。在此，我们指出观测到的Tc和Tc2值与Tc与键价和参数V+（由晶体学键长计算得出）之间长期存在的相关性完全一致。这表明OP中的Tc2与OP的局部结构完全一致，其中顶端氧的存在会降低V+(OP)的值，进而使Tc2相应降低。仿佛在单一1234化合物中存在两个大致解耦的超导体，它们各自的配对温度由其局部最近邻结构决定，反映了极短程的物理特性。
英文摘要
In a recent Letter, Sun et al. report photoemission spectroscopy measurements on the four-layer cuprate (Cu,C)Ba2Ca3Cu4O11 (CuC-1234) in which they resolve two superconducting gaps associated with the inner (IP) and outer (OP) CuO2 planes. CuC-1234 has a Tc as 117 K in a sample previously structurally characterized using neutron powder diffraction. From the Luttinger sum, the beta-band of the IP was found to be heavily underdoped (p~0.07) while the OP alpha2 bonding band was strongly overdoped (p~0.25). Each revealed a gap with very different momentum and temperature dependences. A large gap on the beta band was found to close at the bulk Tc, while a smaller gap on the alpha2 band closed at 70 K. Such two-gap behavior would indicate weak-coupling between the IP and OP, resulting in a second gap-opening temperature, Tc2, and implying a two-step development of the superfluid density on cooling, first on the IPs then on the OPs. Here, we point out that the observed values of Tc and Tc2 are fully consistent with a long-standing correlation of Tc with a bond-valence sum parameter, V+, calculated from the crystallographic bond lengths. This suggests that Tc2 in the OP is entirely consistent with the local structure of the OP where the value of V+(OP) is reduced by the presence of the apical oxygens and Tc2 reduced accordingly. It is as though two largely decoupled superconductors are present in the single 1234 compound and their individual pairing temperatures are determined by their local nearest-neighbour structure, reflecting the very short-range physics.
CommentsComment on arXiv:2507.03921; 1 Page, 1 Figure
