Li Yu, Yin Zhiping, Wang Xiancheng, Tam David W, Abernathy D L, Podlesnyak A, Zhang Chenglin, Wang Meng, Xing Lingyi, Jin Changqing, Haule Kristjan, Kotliar Gabriel, Maier Thomas A, Dai Pengcheng
Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, China.
Phys Rev Lett. 2016 Jun 17;116(24):247001. doi: 10.1103/PhysRevLett.116.247001.
We use neutron scattering to study spin excitations in single crystals of LiFe_{0.88}Co_{0.12}As, which is located near the boundary of the superconducting phase of LiFe_{1-x}Co_{x}As and exhibits non-Fermi-liquid behavior indicative of a quantum critical point. By comparing spin excitations of LiFe_{0.88}Co_{0.12}As with a combined density functional theory and dynamical mean field theory calculation, we conclude that wave-vector correlated low energy spin excitations are mostly from the d_{xy} orbitals, while high-energy spin excitations arise from the d_{yz} and d_{xz} orbitals. Unlike most iron pnictides, the strong orbital selective spin excitations in the LiFeAs family cannot be described by an anisotropic Heisenberg Hamiltonian. While the evolution of low-energy spin excitations of LiFe_{1-x}Co_{x}As is consistent with the electron-hole Fermi surface nesting conditions for the d_{xy} orbital, the reduced superconductivity in LiFe_{0.88}Co_{0.12}As suggests that Fermi surface nesting conditions for the d_{yz} and d_{xz} orbitals are also important for superconductivity in iron pnictides.
我们利用中子散射来研究LiFe₀.₈₈Co₀.₁₂As单晶中的自旋激发，该晶体位于LiFe₁₋ₓCoₓAs超导相的边界附近，并表现出指示量子临界点的非费米液体行为。通过将LiFe₀.₈₈Co₀.₁₂As的自旋激发与密度泛函理论和动态平均场理论的联合计算进行比较，我们得出结论，波矢相关的低能自旋激发主要来自dₓᵧ轨道，而高能自旋激发则来自dᵧz和dₓz轨道。与大多数铁基氮化物不同，LiFeAs族中强烈的轨道选择性自旋激发不能用各向异性海森堡哈密顿量来描述。虽然LiFe₁₋ₓCoₓAs的低能自旋激发的演化与dₓᵧ轨道的电子 - 空穴费米面嵌套条件一致，但LiFe₀.₈₈Co₀.₁₂As中降低的超导性表明，dᵧz和dₓz轨道的费米面嵌套条件对铁基氮化物的超导性也很重要。
