Spin-wave study of a new pyrochlore Heisenberg antiferromagnet - Gd2Pt2O7

We propose a study of the spin-waves of a newly synthesised AF pyrochlore antiferromagnet, Gd2Pt2O7 on LET in zero field. Previous polarized neutron diffraction experiments on our isotopically enriched sample reveal a low temperature co-planar k=0 magnetic structure, akin to Gd2Sn2O7. However further near neighbour exchanges via the 5d Pt eg orbitals are likely, manifesting in an enhanced T_N. Monte-Carlo modelling of the paramagnetic S(Q) supports this picture, but direct measurements of the spin-waves are now required to quantify the level of further near neighbour exchange. We have a 0.25 g sample, which from previous experience (on Gd2Ti2O7 samples of similar mass on CNCS and DCS) is sufficient mass to see the spin waves. We ask for 2 days on LET to complete this study.