该研究团队通过将热力学磁化噪声的超灵敏光学检测与蒙特卡罗模拟相结合，揭示了人工“俄罗斯方块冰”中磁激发的涌现机制。在某些外加磁场下，他们观察到本征噪声显著增加，这预示着分数化激发的自发扩散。这些分数化激发能够沿着俄罗斯方块冰晶格中的特定准一维自旋链独立扩散，而不需要消耗能量。
据悉，直接探测自发的自旋涨落，或称为“磁化噪声”，正逐渐成为揭示和研究自然和人工阻挫磁铁中磁激发的有力手段。根据晶格和阻挫的性质，这些激发通常可以被描述为具有有效磁荷的分数化准粒子。
附：英文原文
Title: Deconstructing magnetization noise: Degeneracies, phases, and mobile fractionalized excitations in tetris artificial spin ice
Author: Goryca, Mateusz, Zhang, Xiaoyu, Ramberger, Justin, Watts, Justin D., Nisoli, Cristiano, Leighton, Chris, Schiffer, Peter, Crooker, Scott A.
Issue&Volume: 2023-10-18
Abstract: Direct detection of spontaneous spin fluctuations, or “magnetization noise,” is emerging as a powerful means of revealing and studying magnetic excitations in both natural and artificial frustrated magnets. Depending on the lattice and nature of the frustration, these excitations can often be described as fractionalized quasiparticles possessing an effective magnetic charge. Here, by combining ultrasensitive optical detection of thermodynamic magnetization noise with Monte Carlo simulations, we reveal emergent regimes of magnetic excitations in artificial “tetris ice.” A marked increase of the intrinsic noise at certain applied magnetic fields heralds the spontaneous proliferation of fractionalized excitations, which can diffuse independently, without cost in energy, along specific quasi-1D spin chains in the tetris ice lattice.
DOI: 10.1073/pnas.2310777120
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2310777120