Probing spin order via magnon transmission across quantum Hall ferromagnet heterojunctions

@misc{lee2026probing,
  title = {{Probing spin order via magnon transmission across quantum Hall ferromagnet heterojunctions}},
  author = {Seung Hwan Lee and Shaowen Chen and Andrew T. Pierce and Patrick R. Forrester and Kenji Watanabe and Takashi Taniguchi and Amir Yacoby},
  howpublished = {arXiv},
  year = {2026},
  month = aug,
  doi = {10.48550/arxiv.2608.29015},
  eprint = {2608.29015},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2608.29015},
}

TY  - UNPB
TI  - Probing spin order via magnon transmission across quantum Hall ferromagnet heterojunctions
AU  - Seung Hwan Lee
AU  - Shaowen Chen
AU  - Andrew T. Pierce
AU  - Patrick R. Forrester
AU  - Kenji Watanabe
AU  - Takashi Taniguchi
AU  - Amir Yacoby
PY  - 2026
DA  - 2026/08/29
PB  - arXiv
DO  - 10.48550/arxiv.2608.29015
UR  - https://arxiv.org/abs/2608.29015
AB  - 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.
ER  -