Quantitative Determination of Quantum Fluctuations in Clean Magnets I: Neutron Spin Echo

Fuente: arXiv
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Autore principale: Xu, Fanjun
Natura: Preprint
Pubblicazione: 2026
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author Xu, Fanjun
author_facet Xu, Fanjun
contents Starting from the magnetic total-moment sum rule of neutron scattering, we derive an explicit connection between ordered-moment reduction and the long-time limit of the intermediate scattering function. We show that this time-domain formulation establishes a direct and experimentally accessible measure of quantum fluctuation strength through neutron spin-echo spectroscopy, with \[P(t\rightarrow\infty)=\frac{I(Q,t\rightarrow\infty)}{I(Q,t=0)}=\frac{\langle μ\rangle^{2}}{\langle μ^{2} \rangle}\] This identity links the long-time polarization to the ratio between ordered and total magnetic moments. Linear spin-wave calculations for square and triangular Heisenberg antiferromagnets demonstrate that both quantum spin reduction and geometric frustration suppress the plateau value in quantitative agreement with moment reduction. The resulting framework establishes a direct and model-independent measure of the level of quantum fluctuations in bulk quantum magnets, particularly for polycrystalline samples.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02431
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantitative Determination of Quantum Fluctuations in Clean Magnets I: Neutron Spin Echo
Xu, Fanjun
Strongly Correlated Electrons
Starting from the magnetic total-moment sum rule of neutron scattering, we derive an explicit connection between ordered-moment reduction and the long-time limit of the intermediate scattering function. We show that this time-domain formulation establishes a direct and experimentally accessible measure of quantum fluctuation strength through neutron spin-echo spectroscopy, with \[P(t\rightarrow\infty)=\frac{I(Q,t\rightarrow\infty)}{I(Q,t=0)}=\frac{\langle μ\rangle^{2}}{\langle μ^{2} \rangle}\] This identity links the long-time polarization to the ratio between ordered and total magnetic moments. Linear spin-wave calculations for square and triangular Heisenberg antiferromagnets demonstrate that both quantum spin reduction and geometric frustration suppress the plateau value in quantitative agreement with moment reduction. The resulting framework establishes a direct and model-independent measure of the level of quantum fluctuations in bulk quantum magnets, particularly for polycrystalline samples.
title Quantitative Determination of Quantum Fluctuations in Clean Magnets I: Neutron Spin Echo
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2603.02431