title: Verification of Anderson Superexchange in MnO via Magnetic Pair Distribution Function Analysis and ab initio Theory.
abstract: We present a temperature-dependent atomic and magnetic pair distribution function (PDF) analysis of neutron total scattering measurements of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. The known antiferromagnetic ground-state structure fits the low-temperature data closely with refined parameters that agree with conventional techniques, confirming the reliability of the newly developed magnetic PDF method. The measurements performed in the paramagnetic phase reveal significant short-range magnetic correlations on a ∼1  nm length scale that differ substantially from the low-temperature long-range spin arrangement. Ab initio calculations using a self-interaction-corrected local spin density approximation of density functional theory predict magnetic interactions dominated by Anderson superexchange and reproduce the measured short-range magnetic correlations to a high degree of accuracy. Further calculations simulating an additional contribution from a direct exchange interaction show much worse agreement with the data. The Anderson superexchange model for MnO is thus verified by experimentation and confirmed by ab initio theory.
authors.affiliation: Department of Physics, Columbia University, New York, New York 10027, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Frandsen
authors.affiliation: Swiss Norwegian Beamlines, European Synchrotron Radiation Facility (ESRF), 38000 Grenoble, France.
authors.forename: Michela
authors.initials: M
authors.lastname: Brunelli
authors.affiliation: Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Katharine
authors.initials: K
authors.lastname: Page
authors.affiliation: Department of Physics, Columbia University, New York, New York 10027, USA.
authors.forename: Yasutomo J
authors.initials: YJ
authors.lastname: Uemura
authors.affiliation: Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom.
authors.forename: Julie B
authors.initials: JB
authors.lastname: Staunton
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.|Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA.
authors.forename: Simon J L
authors.initials: SJ
authors.lastname: Billinge