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arXiv · 2208.12369

Pinch points and half-moons in dipolar-octupolar Nd$_2$Hf$_2$O$_7$

A. Samartzis·J. Xu·V. K. Anand·A. T. M. N. Islam·J. Ollivier·Y. Su·B. Lake
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Abstract

While it is established that the pinch point scattering pattern in spin ice arises from an emergent coulomb phase associated with magnetic moment that is divergence-free, more complex Hamiltonians can introduce a divergence-full part. If these two parts remain decoupled, they give rise to the co-existence of distinct features. Here we show that the moment in ${\rm Nd_2Hf_2O_7}$ forms a static long-range ordered ground state, a flat, gapped pinch point excitation and dispersive excitations. These results confirm recent theories which predict that the dispersive modes, which arise from the divergence-full moment, host a pinch point pattern of their own, observed experimentally as `half-moons'.

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A. Samartzis, J. Xu, V. K. Anand, A. T. M. N. Islam, J. Ollivier, Y. Su, B. Lake. 2022-08-25. Pinch points and half-moons in dipolar-octupolar Nd$_2$Hf$_2$O$_7$. https://doi.org/10.1103/physrevb.106.l100401

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