论文标题
通过折叠和未填充的铁砷化的阶段来控制T $ _C $
Controlling T$_c$ through band structure and correlation engineering in collapsed and uncollapsed phases of iron arsenides
论文作者
论文摘要
最新观察到lafe $ _2 $的未收获（倒塌）四方阶段的超导率的选择性出现（抑制）重新兴趣，重新兴趣了解频段结构的哪些特征控制超导t $ _c $。我们表明，狭窄的fe-d $ _ {xy} $状态与费米能量的接近是主要因素。在未填充的阶段中，该状态处于费米能量，并且在单个粒子通道和两个粒子通道中最密切相关和增强散射的来源。由此产生的强度和宽的低能自旋波动抑制磁积水，并同时为库珀对形成提供胶水。在折叠的四方阶段中，d $ _ {xy} $状态的驱动远低于费米能量，这抑制了低能散射并阻止了超导性。 Cafe $ _ {2} $的无胶囊和折叠阶段的类似宽自旋激发的来源出现在$ _ {2} $中。这表明控制连贯性提供了一种方法，可以在非常规上介导的非常规超导体中设计t $ _c $。
Recent observations of selective emergence (suppression) of superconductivity in the uncollapsed (collapsed) tetragonal phase of LaFe$_2$As$_2$ has rekindled interest in understanding what features of the band structure control the superconducting T$_c$. We show that the proximity of the narrow Fe-d$_{xy}$ state to the Fermi energy emerges as the primary factor. In the uncollapsed phase this state is at the Fermi energy, and is most strongly correlated and source of enhanced scattering in both single and two particle channels. The resulting intense and broad low energy spin fluctuations suppress magnetic ordering and simultaneously provide glue for Cooper pair formation. In the collapsed tetragonal phase, the d$_{xy}$ state is driven far below the Fermi energy, which suppresses the low-energy scattering and blocks superconductivity. A similar source of broad spin excitation appears in uncollapsed and collapsed phases of CaFe$_{2}$As$_{2}$. This suggests controlling coherence provides a way to engineer T$_c$ in unconventional superconductors primarily mediated through spin fluctuations.
