title: Orbital Selective Spin Excitations and their Impact on Superconductivity of LiFe_{1-x}Co_{x}As.
abstract: 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.
authors.affiliation: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Li
authors.affiliation: Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, China.|Department of Physics, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Yin
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Xiancheng
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Tam
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Abernathy
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: A
authors.initials: A
authors.lastname: Podlesnyak
authors.affiliation: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors.forename: Chenglin
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720, USA.
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Lingyi
authors.initials: L
authors.lastname: Xing
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.|Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Changqing
authors.initials: C
authors.lastname: Jin
authors.affiliation: Department of Physics, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Kristjan
authors.initials: K
authors.lastname: Haule
authors.affiliation: Department of Physics, Rutgers University, Piscataway, New Jersey 08854, USA.|Brookhaven National Laboratory, Upton, New York 11973-5000, USA.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Kotliar
authors.affiliation: Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Maier
authors.affiliation: 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.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Dai