基于表面掺杂理解钡与菲、蒽合成分子晶体中的超导电性

Understanding Superconducting Property in Synthesized Molecular Crystals of Barium and Phenanthrene/Anthracene Based on Surface Doping

摘要: 本文采用基于密度泛函理论的第一性原理计算方法，从表面掺杂的角度系统地研究了钡与菲、蒽合成材料的晶体结构和电子结构，旨在解释实验发现的超导现象。计算结果表明沿c轴方向和a轴方向的两个钡掺杂菲构型呈现出非磁金属态，在费米能级处的态密度值分别为5.69 states/eV/unit和9.31 states/eV/ unit；沿a轴方向和b轴方向的两个钡掺杂蒽构型也表现为非磁金属态，在费米能级处的态密度值分别为11.02 states/eV/unit和23.47 states/eV/unit。分波态密度显示费米能级处的电子态主要来源于C-2p轨道，而C-2s和Ba-6s轨道可以忽略不计。这些结果合理地解释了实验发现钡掺杂菲、蒽中的多个超导相。研究工作表明金属表面掺杂相比于体掺杂芳香烃分子晶体更容易实现超导电性，从而为新型有机高温超导材料的设计与合成奠定了重要的理论基础。

Abstract: This paper employs first-principles calculations based on the density functional theory to investigate the crystal and electronic structures of barium-doped phenanthrene (PHN) and anthracene (AN) from the perspective of surface doping, aiming to elucidate the experimentally observed superconducting phenomena. The computational results reveal that two barium-doped PHN configurations along the c-axis and a-axis directions exhibit nonmagnetic metallic states, with density of states at the Fermi level being 5.69 states/eV/unit and 9.31 states/eV/unit, respectively. Two barium-doped AN configurations along the a-axis and b-axis directions also demonstrate nonmagnetic metallic characteristics, showing density of states of 11.02 states/eV/unit and 23.47 states/eV/unit at the Fermi level. The projected density of states indicates that the electronic states near the Fermi level primarily originate from the C-2p orbitals, with negligible contributions from the C-2s and Ba-6s orbitals. These findings provide a reasonable explanation for the multiple superconducting phases observed in barium-doped PHN and AN materials. This research demonstrates that surface doping of aromatic hydrocarbon molecular crystals is more effective than bulk doping in achieving superconductivity, thereby laying an important theoretical foundation for the design and synthesis of novel organic high-temperature superconducting materials.