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  Samartzis, A.; Xu, J.; Anand, V.K.; Islam, A.T.M.N.; Ollivier, J.; Su, Y.; Lake, B.: Pinch points and half-moons in dipolar-octupolar Nd₂Hf₂O₇. Physical Review B 106 (2022), p. L100401/1-6

10.1103/physrevb.106.l100401
Open Access Version (externer Anbieter)

Abstract:
While it is established that the pinch point scattering pattern in spin ice arises from an emergent Coulomb phase associated with a 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 coexistence of distinct features. Here, we show that the moment in Nd2Hf2O7 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.”