Spin Correlations in the Dipolar Pyrochlore Antiferromagnet Gd2Sn2O7

摘要: We investigate spin correlations in the dipolar Heisenberg antiferromagnet Gd2Sn2O7 using polarised neutron-scattering measurements correlated paramagnetic regime. Using Monte Carlo methods, we show that our data are sensitive to weak further-neighbour exchange interactions of magnitude ~0.5% nearest-neighbour interaction, and compatible with either antiferromagnetic next-nearest neighbour interactions, or ferromagnetic third-neighbour connect spins across hexagonal loops. Calculations magnetic scattering intensity reveal rods diffuse along [111] reciprocal-space directions, which explain terms strong parallel set directions a given its nearest neighbours. Finally, demonstrate highly anisotropic, separations particularly critical fluctuations associated incipient long-range order.