Frustration and short range magnetic correlations in the pyrochlore Y2Mn2O7 (abstract)

The bulk magnetic susceptibility of Y2Mn2O7 is suggestive of ferromagnetic order, θc=+40 K, apparent Tc=25 K. However, both dc and ac susceptibility data show a broad maximum near 6 K which is frequency and field dependent. Heat capacity studies to 2 K show no evidence for long range magnetic order. Also, neutron scattering data indicate the presence of short range correlations. These results are compared to mean field theory predictions for the highly frustrated 16c sites in the pyrochlore lattice.