title: Spin state transition in LaCoO3 studied using soft x-ray absorption spectroscopy and magnetic circular dichroism.
abstract: Using soft x-ray absorption spectroscopy and magnetic circular dichroism at the Co-L(2,3) edge, we reveal that the spin state transition in LaCoO3 can be well described by a low-spin ground state and a triply degenerate high-spin first excited state. From the temperature dependence of the spectral line shapes, we find that LaCoO3 at finite temperatures is an inhomogeneous mixed-spin state system. It is crucial that the magnetic circular dichroism signal in the paramagnetic state carries a large orbital momentum. This directly shows that the currently accepted low- or intermediate-spin picture is at variance. Parameters derived from these spectroscopies fully explain existing magnetic susceptibility, electron spin resonance, and inelastic neutron data.
authors.affiliation: II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany.
authors.forename: M W
authors.initials: MW
authors.lastname: Haverkort
authors.forename: Z
authors.initials: Z
authors.lastname: Hu
authors.forename: J C
authors.initials: JC
authors.lastname: Cezar
authors.forename: T
authors.initials: T
authors.lastname: Burnus
authors.forename: H
authors.initials: H
authors.lastname: Hartmann
authors.forename: M
authors.initials: M
authors.lastname: Reuther
authors.forename: C
authors.initials: C
authors.lastname: Zobel
authors.forename: T
authors.initials: T
authors.lastname: Lorenz
authors.forename: A
authors.initials: A
authors.lastname: Tanaka
authors.forename: N B
authors.initials: NB
authors.lastname: Brookes
authors.forename: H H
authors.initials: HH
authors.lastname: Hsieh
authors.forename: H-J
authors.initials: HJ
authors.lastname: Lin
authors.forename: C T
authors.initials: CT
authors.lastname: Chen
authors.forename: L H
authors.initials: LH
authors.lastname: Tjeng