LiFeAs超导体中磁性与声子软化

摘要

运用第一性原理密度泛函理论研究了铁基超导体LiFeAs的电子结构和声子谱．计算得到的LiFeAs基态具有涨落的条型反铁磁构型．通过比较LiFeAs在非磁态与条形反铁磁态下的声子态密度，发现，LiFeAs中各向异性自旋互作用的竞争产生了不稳定的自旋密度波和部分品格位置弛豫，导致Fe和As原子振动模式的软化，从而提高电声子耦合强度．因此，自旋一声子互作用对非常规超导电性有重要贡献．%Using the first principles calculations based on density functional theory, we study the electronic band structure, the phonon dispersion, and the phonon density of states of the iron-based superconductor LiFeAs. The obtained ground state of LiFeAs is of the fluctuated antiferromagnetic order and partial structural relaxation. A comparson of phonon densities of states between in the striped antiferromagnetic ordering and in the nonmagnetic state indicates that the anisotropic spin interactions result in phonon softening of Fe and As atomic vibrations, thereby enhancing the electron-phonon coupling. As a result, the spin-phonon interaction plas an important role in the unconventional superconductivity.