论文标题
nematicity在控制自旋波动和超导TC中的作用
Role of nematicity in controlling spin fluctuations and superconducting Tc in bulk FeSe
论文作者
论文摘要
FESE在90 \ k处从四方到略微正骨相的过渡，并成为8 \，k以下的超导体。正骨架阶段有时被称为列相，因为量子振荡，中子和其他测量值检测到$ x $和$ y $中的明显不对称性。 nematicity如何影响超导性，最近已成为强烈猜测的问题。在这里，我们采用了高级\ emph {ab-initio}格林的超导性功能描述，并表明散装四方FESE原则上将具有几乎相同的t $ _ {C} $的超导体。尚不清楚推动观察到的nematicity的机制。由于目前的理论低估了nematicity，我们通过人为地增强正交畸变来模拟全态不对称。为了进行基准测试，我们将理论自旋敏感性与实验观察到的所有能量和相关动量的数据进行了比较。当调整正交畸变以与旋转易感性的观察到的夜间性相关时，增强的nematicity在Fe-3D $ _ {XZ} $和D $ _ {Yz} $ ORBITALS中导致光谱重量重新分布，但是它最多可导致最多10-15 $ \％$ \ \％$ $ \ colement in t $ _} c} c} c} c} c}这是因为d $ _ {xy} $轨道始终是最密切相关的，并提供了超导胶的大部分来源。 nematicity在费米水平上抑制状态的密度；尽管如此，t $ _ {c} $增加，与BCS和BEC理论相矛盾。我们展示了增加的增加与粒子粒子顶点的结构有关。我们的结果表明，虽然非神经性可能是大量FESE的固有特性，但并不是驱动超导配对的主要力。
FeSe undergoes a transition from a tetragonal to a slightly orthorhombic phase at 90\,K, and becomes a superconductor below 8\,K. The orthorhombic phase is sometimes called a nematic phase because quantum oscillation, neutron, and other measurements detect a significant asymmetry in $x$ and $y$. How nematicity affects superconductivity has recently become a matter of intense speculation. Here we employ an advanced \emph{ab-initio} Green's function description of superconductivity and show that bulk tetragonal FeSe would, in principle, superconduct with almost the same T$_{c}$ as the nematic phase. The mechanism driving the observed nematicity is not yet understood. Since the present theory underestimates nematicity, we simulate the full nematic asymmetry by artificially enhancing the orthorhombic distortion. For benchmarking, we compare theoretical spin susceptibilities against experimentally observed data over all energies and relevant momenta. When the orthorhombic distortion is adjusted to correlate with observed nematicity in spin susceptibility, the enhanced nematicity causes spectral weight redistribution in the Fe-3d$_{xz}$ and d$_{yz}$ orbitals, but it leads to at most 10-15$\%$ increment in T$_{c}$. This is because the d$_{xy}$ orbital always remains the most strongly correlated and provides most of the source of the superconducting glue. Nematicity suppresses the density of states at Fermi level; nevertheless T$_{c}$ increases, in contradiction to both BCS and BEC theories. We show how the increase is connected to the structure of the particle-particle vertex. Our results suggest while nematicity may be intrinsic property of bulk FeSe, is not the primary force driving the superconducting pairing.
