发表机构
Harvard University; National Institute for Materials Science（哈佛大学; 国立材料研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究在单层-双层石墨烯量子霍尔铁磁异质结中首次实现磁振子传输，探测到双层石墨烯的自旋序，确立了异质结磁振子传输作为模块化磁有序探针的新方法。
AI 中文摘要
二维材料平台如今承载着从非常规超导体到分数量子陈绝缘体等一系列奇异的关联相。探测这些体系中的磁有序对理解其 underlying 物理至关重要，但稀疏的自旋密度使得传统磁探针失效。量子霍尔铁磁体（QHFM）中的自旋波（即磁振子）已被证明可有效探测石墨烯体系中各种对称性破缺的量子霍尔（QH）相的磁有序，但此前的工作仅局限于单一材料内的同质结构型。本文展示了单层-双层石墨烯量子霍尔铁磁异质结中的磁振子传输——这是首次实现量子霍尔铁磁异质结间的磁振子传输，利用一种材料作为磁振子源来探测另一种不同材料的磁有序。在单层石墨烯（MLG）的填充因子ν=1处产生磁振子，我们通过非局域电压测量检测到其穿过双层石墨烯（BLG）的传输，揭示了BLG对称性破缺量子霍尔态中的自旋序。该传输呈现出典型的磁振子特征：在塞曼能处急剧启动，并随朗道能级填充系统性变化，包括在自旋极化消失的ν=4和8处受到抑制。我们的发现确立了异质结磁振子传输作为一种强大、模块化的磁有序探针，为在快速扩展的二维材料家族中研究奇异量子态开辟了新途径。
英文摘要
Two-dimensional material platforms now host a remarkable array of exotic correlated phases, from unconventional superconductivity to fractional Chern insulators. Probing magnetic order in these systems is essential for understanding their underlying physics, yet dilute spin densities render conventional magnetic probes ineffective. Spin waves, or magnons, in quantum Hall ferromagnets (QHFM) have proven effective for probing the magnetic order in various symmetry-broken quantum Hall (QH) phases in graphene systems, but previous works have been limited to homojunction configurations within a single material. Here, we demonstrate magnon transmission across a monolayer-bilayer graphene quantum Hall ferromagnet heterojunction - the first magnon transmission across quantum Hall ferromagnet heterojunctions, using one material as a magnon source to probe magnetic order in a distinct material. Generating magnons in monolayer graphene (MLG) at $ν$ = 1, we detect their transmission through bilayer graphene (BLG) via nonlocal voltage measurements, revealing spin order in BLG symmetry-broken quantum Hall states. The transmission exhibits hallmark magnon signatures: a sharp onset at the Zeeman energy and systematic variation with Landau level filling, including suppression at $ν$ = 4 and 8 where spin polarization vanishes. Our findings establish heterojunction magnon transmission as a powerful, modular probe of magnetic order, opening new avenues for investigating exotic quantum states across the rapidly expanding family of two-dimensional materials.
Comments39 pages, 15 figures (4 main, 11 extended data)
