Long- and short-range magnetism in the frustrated double perovskite Ba2MnWO6

The structural and magnetic properties of the face-centered-cubic double perovskite Ba2MnWO6 were investigated using neutron powder diffraction, DC magnetometry, muon spin relaxation, and inelastic neutron scattering. Ba2MnWO6 undergoes type II long-range antiferromagnetic ordering at a Neel temperature of 8(1) K with a frustration index, f approximate to 8. Inelastic neutron scattering was used to identify the magnetic coupling constants J(1) and J(2), which were found to equal -0.080 and -0.076 meV, respectively. This indicates that both of the magnetic coupling constants are antiferromagnetic with similar magnitudes, which is in contrast to other known 3d metal double perovskites of the form Ba2MWO6. Above the Neel temperature, muon spin-relaxation measurements and inelastic neutron-scattering techniques identify a short-range correlated magnetic state that is similar to that observed in the archetypical face-centered-cubic lattice antiferromagnet MnO.