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arXiv · 1608.05062

Spin Correlations in the Dipolar Pyrochlore Antiferromagnet Gd2Sn2O7

Joseph A. M. Paddison·Georg Ehlers·Oleg A. Petrenko·Andrew R. Wildes·Jason S. Gardner·J. Ross Stewart
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Abstract

We investigate spin correlations in the dipolar Heisenberg antiferromagnet Gd2Sn2O7 using polarised neutron-scattering measurements in the correlated paramagnetic regime. Using Monte Carlo methods, we show that our data are sensitive to weak further-neighbour exchange interactions of magnitude ~0.5% of the nearest-neighbour interaction, and are compatible with either antiferromagnetic next-nearest neighbour interactions, or ferromagnetic third-neighbour interactions that connect spins across hexagonal loops. Calculations of the magnetic scattering intensity reveal rods of diffuse scattering along [111] reciprocal-space directions, which we explain in terms of strong antiferromagnetic correlations parallel to the set of <110> directions that connect a given spin with its nearest neighbours. Finally, we demonstrate that the spin correlations in Gd2Sn2O7 are highly anisotropic, and correlations parallel to third-neighbour separations are particularly sensitive to critical fluctuations associated with incipient long-range order.

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Joseph A. M. Paddison, Georg Ehlers, Oleg A. Petrenko, Andrew R. Wildes, Jason S. Gardner, J. Ross Stewart. 2016-08-17. Spin Correlations in the Dipolar Pyrochlore Antiferromagnet Gd2Sn2O7. https://doi.org/10.1088/1361-648x%2Faa5d2e

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