Coexistence of Ferromagnetic and Stripe Antiferromagnetic Spin Fluctuations in SrCo2As2
Louisiana State University, United States
We use inelastic neutron scattering to study energy and wave vector dependence of spin fluctuations in SrCo2As2, derived from SrFe 2−xCoxAs2 iron pnictide superconductors. Our data reveal the coexistence of antiferromagnetic (AF) and ferromagnetic (FM) spin fluctuations at wave vectors Q AF=(1, 0) and Q FM=(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 e g 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.
Brief CV of Dr. Yu Li:
Yu Li earned his PhD in Physics from Rice University in Houston, TX after he graduated from Renmin University with a master's degree. He is now a postdoctoral researcher in Louisiana Consortium for Neutron Scattering and Department of Physics & Astronomy in Louisiana State University. His past research focused on fundamental interactions between charge, spin, orbital and lattice in iron-based superconductors and the resultant novel quantum phases, for instance, unconventional superconductivity and electronic/spin nematicity. His current interests include searching for topological objects in various non-centrosymmetric magnetic material and studying their dynamic behaviors.