Verification of Anderson Superexchange in MnO via Magnetic Pair Distribution Function Analysis and ab initio Theory

Benjamin A. Frandsen, Michela Brunelli, Katharine Page, Yasutomo J. Uemura, Julie B. Staunton, and Simon J. L. Billinge

Phys. Rev. Lett. 116, 197204 – Published 11 May 2016

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 $\sim 1 nm$ 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.

Received 30 December 2015

DOI:https://doi.org/10.1103/PhysRevLett.116.197204

Physics Subject Headings (PhySH)

Paramagnetism

Oxides

Inelastic neutron scattering

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Benjamin A. Frandsen¹, Michela Brunelli², Katharine Page³, Yasutomo J. Uemura¹, Julie B. Staunton⁴, and Simon J. L. Billinge^5,6,*

¹Department of Physics, Columbia University, New York, New York 10027, USA
²Swiss Norwegian Beamlines, European Synchrotron Radiation Facility (ESRF), 38000 Grenoble, France
³Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
⁴Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
⁵Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
⁶Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA