Coexistence of Ferromagnetic and Stripe Antiferromagnetic Spin Fluctuations in SrCo2As2

Yu Li, Zhiping Yin, Zhonghao Liu, Weiyi Wang, Zhuang Xu, Yu Song, Long Tian, Yaobo Huang, Dawei Shen, D. L. Abernathy, J. L. Niedziela, R. A. Ewings, T. G. Perring, Daniel M. Pajerowski, Masaaki Matsuda, Philippe Bourges, Enderle Mechthild, Yixi Su, Pengcheng Dai

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Abstract

We use inelastic neutron scattering to study energy and wave vector dependence of spin fluctuations in SrCo2As2, derived from SrFe2-xCoxAs2 iron pnictide superconductors. Our data reveal the coexistence of antiferromagnetic (AF) and ferromagnetic (FM) spin fluctuations at wave vectors QAF=(1,0) and QFM=(0,0)/(2,0), respectively. By comparing neutron scattering results with those of dynamic mean field theory calculation and angle-resolved photoemission spectroscopy experiments, we conclude that both AF and FM spin fluctuations in SrCo2As2 are closely associated with a flatband of the eg orbitals near the Fermi level, different from the t2g orbitals in superconducting SrFe2-xCoxAs2. Therefore, Co substitution in SrFe2-xCoxAs2 induces a t2g to eg orbital switching, and is responsible for FM spin fluctuations detrimental to the singlet pairing superconductivity.

Original languageEnglish
Article number117204
JournalPhysical Review Letters
Volume122
Issue number11
DOIs
StatePublished - Mar 21 2019

Funding

The work at Rice is supported by the U.S. NSF DMR-1700081 and the Robert A. Welch Foundation Grant No. C-1839 (P. D.). Z. P. Y. was supported by the NSFC (Grant No. 11674030), the Fundamental Research Funds for the Central Universities (Grant No. 310421113), the National Key Research and Development Program of China Grant No. 2016YFA0302300. The calculations used high performance computing clusters at BNU in Zhuhai and the National Supercomputer Center in Guangzhou. Z. H. L. acknowledges the NSFC (Grant No. 11704394), and the Shanghai Sailing Program (Grant No. 17YF1422900). This research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Experiments at the ISIS Neutron and Muon Source were supported by a beam time allocation RB1610397a from the Science and Technology Facilities Council. The work at Rice is supported by the U.S. NSF DMR-1700081 and the Robert A. Welch Foundation Grant No. C-1839 (P. D.). Z. P. Y. was supported by the NSFC (Grant No. 11674030), the Fundamental Research Funds for the Central Universities (Grant No. 310421113), the National Key Research and Development Program of China Grant No. 2016YFA0302300. The calculations used high performance computing clusters at BNU in Zhuhai and the National Supercomputer Center in Guangzhou. Z. H. L. acknowledges the NSFC (Grant No. 11704394), and the Shanghai Sailing Program (Grant No. 17YF1422900). This research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Experiments at the ISIS Neutron and Muon Source were supported by a beam time allocation RB1610397 from the Science and Technology Facilities Council.

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