Orbital Selective Spin Excitations and their Impact on Superconductivity of LiFe1-xCoxAs

Yu Li, Zhiping Yin, Xiancheng Wang, David W. Tam, D. L. Abernathy, A. Podlesnyak, Chenglin Zhang, Meng Wang, Lingyi Xing, Changqing Jin, Kristjan Haule, Gabriel Kotliar, Thomas A. Maier, Pengcheng Dai

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33 Scopus citations

Abstract

We use neutron scattering to study spin excitations in single crystals of LiFe0.88Co0.12As, which is located near the boundary of the superconducting phase of LiFe1-xCoxAs and exhibits non-Fermi-liquid behavior indicative of a quantum critical point. By comparing spin excitations of LiFe0.88Co0.12As 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 dxy orbitals, while high-energy spin excitations arise from the dyz and dxz 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 LiFe1-xCoxAs is consistent with the electron-hole Fermi surface nesting conditions for the dxy orbital, the reduced superconductivity in LiFe0.88Co0.12As suggests that Fermi surface nesting conditions for the dyz and dxz orbitals are also important for superconductivity in iron pnictides.

Original languageEnglish
Article number247001
JournalPhysical Review Letters
Volume116
Issue number24
DOIs
StatePublished - Jun 17 2016

Funding

The neutron scattering work at Rice is supported by the U.S. DOE, BES DE-SC0012311 (P.D.). The computational work at Rice, ORNL, and Rutgers is supported by NSF DMR-1436006 (P.D.), DMR-1308603 (T.M.), DMR-1405303 (K.H.), and DMR-1435918 (Z.P.Y. and G.K.). The materials effort at Rice is also supported by the Robert A. Welch Foundation Grant No.C-1839 (P.D.). The research at SNS was sponsored by the Scientific User Facilities Division, BES, U.S. DOE. The research used resources of the Oak Ridge Leadership Computing Facility at ORNL, which is supported by U.S. DOE under Contract No. DE-AC05-00OR22725. The work at IOP, CAS is supported by NSFC and MOST of China through research projects.

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