Power-law spin correlations in pyrochlore antiferromagnets

Depleted pyrochlore antiferromagnets

I consider the class of “depleted pyrochlore” lattices of corner-sharing triangles, made by removing spins from a pyrochlore lattice such that every tetrahedron loses exactly one. Previously known examples are the “hyperkagome” and “kagome staircase”. I give criteria in terms of loops for whether a given depleted lattice can order analogous to the kagome “ √ 3× √ 3” state, and also show how the...

Local Spin Correlations in Heisenberg Antiferromagnets

We use linked cluster series expansion methods to estimate the values of various short distance correlation functions in S = 1/2 Heisenberg antiferromagnets at T = 0, for dimension d = 1, 2, 3. The method incorporates the possibility of spontaneous symmetry breaking, which is manifest in d = 2, 3. The results are important in providing a test for approximate theories of the antiferromagnetic gr...

Spin correlations in the dipolar pyrochlore antiferromagnet Gd2Sn2O7.

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-nea...

Weyl magnons in breathing pyrochlore antiferromagnets

Frustrated quantum magnets not only provide exotic ground states and unusual magnetic structures, but also support unconventional excitations in many cases. Using a physically relevant spin model for a breathing pyrochlore lattice, we discuss the presence of topological linear band crossings of magnons in antiferromagnets. These are the analogues of Weyl fermions in electronic systems, which we...

Dimensional evolution of spin correlations in the magnetic pyrochlore Yb2Ti2O7