可调胶体人工自旋晶格中Ising耦合的空间分辨重构

中文摘要 AI 辅助

屈曲胶体单层构成了一种多功能的软物质平台，用于构建人工自旋晶格，其中每个粒子充当一个Ising自旋。虽然对于完美粒子晶格，平均Ising耦合能量已被近似推导，但从真实样品中提取完整的耦合参数集仍然难以实现。在此，我们应用一种逆方法，从测量的胶体自旋构型中重构所有最近邻有效Ising耦合能量。我们设计了多种实验方案来控制胶体系统的热力学状态，从各向同性压缩和剪切变形到粒子间吸引力的调制，每种方案都产生不同的自旋构型。利用自旋构型数据，我们通过最大似然估计重构所有最近邻有效Ising耦合能量。为了在没有真实模型参数的情况下评估推断可靠性，我们提出使用估计耦合标准差的收敛性作为实用的、无需真实值的判据，并使用已知参数的模拟数据验证其可靠性。提取的空间分辨耦合揭示了每种控制方案如何影响微观耦合参数的符号、大小、统计分布和空间排列：各向同性压缩增强了反铁磁耦合并增强了淬火无序；剪切变形产生了方向依赖的各向异性耦合；而粒子间吸引力的增加驱动了从反铁磁到顺磁再到铁磁耦合的交叉。这项工作为估计胶体人工自旋晶格的有效模型参数建立了一个实用的推断框架。

英文摘要

Buckled colloidal monolayers constitute a versatile soft-matter platform for engineering artificial spin lattices, with each particle serving as a single Ising spin. While the average Ising coupling energy has been approximately derived for perfect particle lattices, extracting the complete set of coupling parameters from real samples remains inaccessible. Here, we apply an inverse method to reconstruct all nearest-neighbor effective Ising coupling energies from measured colloidal spin configurations. We design multiple experimental protocols to control the thermodynamic state of the colloidal system, from isotropic compression and shear deformation to modulation of interparticle attraction, each giving rise to distinct spin configurations. Using spin configuration data, we reconstruct all nearest-neighbor effective Ising coupling energies using maximum likelihood estimation. To assess inference reliability without ground-truth model parameters, we propose to use the convergence of the standard deviation of the estimated couplings as a practical, ground-truth-free criterion, and validate its reliability using simulation data with known parameters. The extracted spatially resolved couplings reveal how each control protocol influences the sign, magnitude, statistical distribution, and spatial arrangement of the microscopic coupling parameters: isotropic compression strengthens antiferromagnetic couplings and enhances quenched disorder; shear deformation generates direction-dependent anisotropic couplings; and increased interparticle attraction drives a crossover from antiferromagnetic to paramagnetic and then to ferromagnetic couplings. This work establishes a practical inference framework for estimating effective model parameters of colloidal artificial spin lattices.

发表机构

• Southern University of Science and Technology（南方科技大学）

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