Total Moment Sum Rule for Magnets in the Vicinity of Quantum Critical Point

Abstract

It is known that the longitudinal and transverse excitation modes can exist in the vicinity of a quantum critical point in the ordered phase of quantum magnetic systems. The total moment sum rule for such systems is derived on the basis of the extended spin-wave theory, where both longitudinal and transverse magnetic excitations are taken into account. The sum rule is resolved into elastic, one-magnon, and two-magnon components. The formulation is applicable to spin systems with the longitudinal mode, such as $S=1$ systems with single-ion anisotropy of easy-plane type and spin dimer systems. The result helps us analyze and understand measured data of inelastic neutron scattering.

arXiv comment16 pages, 10 figures

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Cited by in corpus (1)

• Neutron scattering sum rules, symmetric exchanges, and helicoidal magnetism in MnSb${}_2$O${}_6$