Ab-initio Studies of (Li${}_{0.8}$Fe${}_{0.2}$)OHFeSe Superconductors: Revealing the Dual Roles of Fe${}_{0.2}$ in Structural Stability and Charge Transfer

Abstract

The recently discovered (Li${}_{0.8}$Fe${}_{0.2}$)OHFeSe superconductor provides a new platform for exploiting the microscopic mechanisms of high-$T_c$ superconductivity in FeSe-derived systems. Using density functional theory calculations, we first show that substitution of Li by Fe not only significantly strengthens the attraction between the (Li${}_{0.8}$Fe${}_{0.2}$)OH spacing layers and the FeSe superconducting layers along the \emph{c} axis, but also minimizes the lattice mismatch between the two in the \emph{ab} plane, both favorable for stabilizing the overall structure. Next we explore the electron injection into FeSe from the spacing layers, and unambiguously identify the Fe${}_{0.2}$ components to be the dominant atomic origin of the dramatically enhanced interlayer charge transfer. We further reveal that the system strongly favors collinear antiferromagnetic ordering in the FeSe layers, but the spacing layers can be either antiferromagnetic or ferromagnetic depending on the Fe${}_{0.2}$ spatial distribution. Based on these understandings, we also predict (Li${}_{0.8}$Co${}_{0.2}$)OHFeSe to be structurally stable with even larger electron injection and potentially higher $T_c$.

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Cited by in corpus (8)

• Monolayer FeSe on SrTiO${}_3$
• Proximity induced superconductivity within the insulating (Li${}_{0.84}$Fe${}_{0.16}$)OH layers in (Li${}_{0.84}$Fe${}_{0.16}$)OHFe${}_{0.98}$Se
• Effects of magnetic dopants in (Li${}_{0.8}$M${}_{0.2}$OH)FeSe (M = Fe, Mn, Co): a density-functional theory study using band unfolding technique
• Quasi two-dimensional nature of high-Tc superconductivity in iron-based (Li,Fe)OHFeSe
• Coexistence of magnetism and superconductivity in separate layers of the iron-based superconductor Li_{1-x}Fe_{x}(OH)Fe_{1-y}Se
• Electronic phase separation in iron selenide (Li, Fe)OHFeSe superconductor system
• Doping Mn into (Li1-xFex)OHFe1-ySe superconducting crystals via ion-exchange and ion-release/introduction syntheses
• Long range magnetic order in hydroxide layer doped (Li${}_{1-x-y}$Fe${}_x$Mn${}_y$OD)FeSe