K. MatanS. IbukaR. MorinagaSongxue ChiJ. W. LynnA. D. ChristiansonM. D. LumsdenT. J. SatoUniversity of TokyoJapan Science and Technology AgencyNIST Center for Neutron ResearchUniversity of MarylandOak Ridge National LaboratoryMahidol University2018-09-242018-09-242010-08-18Physical Review B - Condensed Matter and Materials Physics. Vol.82, No.5 (2010)1550235X109801212-s2.0-77957369645https://repository.li.mahidol.ac.th/handle/20.500.14594/29299The spin dynamics in single crystal, electron-doped Ba( Fe 1-xCox)2As2 has been investigated by inelastic neutron scattering over the full range from undoped to the overdoped regime. We observe damped magnetic fluctuations in the normal state of the optimally doped compound (x=0.06) that share a remarkable similarity with those in the paramagnetic state of the parent compound (x=0). In the overdoped superconducting compound (x=0.14), magnetic excitations show a gaplike behavior, possibly related to a topological change in the hole Fermi surface (Lifshitz transition) while the imaginary part of the spin susceptibility χ″ prominently resembles that of the overdoped cuprates. For the heavily overdoped, nonsuperconducting compound (x=0.24) the magnetic scattering disappears, which could be attributed to the absence of a hole Fermi-surface pocket observed by photoemission. © 2010 The American Physical Society.Mahidol UniversityMaterials SciencePhysics and AstronomyArticleSCOPUS10.1103/PhysRevB.82.054515