2025/10/06 by Luo, Yi, Powell, Matthew, Paddison, Joseph A. M. +4
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2510.04845
We report single crystal neutron spectroscopy and bulk characterization on hydrothermally grown Nd2Sn2O7, revealing magnetic moment fragmentation embedded within the all-in-all-out ordered state. The spectra show a nearly flat band with pinch-point-like momentum dependence, accompanied by dispersive branches that generate half-moon features across multiple Brillouin zones. These defining signatures are captured quantitatively by a minimal dipolar-octupolar spin Hamiltonian, demonstrating excellent agreement between experiment and theory. The higher flat-mode energy helps account for the absence of dynamical interference in prior μSR studies, while the lack of any photon-like excitation imposes strict constraints on the proposed Coulombic antiferromagnet scenario. Our results extend moment fragmentation to Nd2Sn2O7 and identify it as a clean, tractable platform for quantitative exploration of emergent gauge field physics and multipolar spin-wave dynamics in frustrated magnets.