Low-Loss Charge Transfer Plasmons in Graphene/α-RuCl<sub>3</sub> Heterostructures Below 40 K
Charge transfer at material interfaces governs a wide range of physical properties, from electronic band structures to emergent collective excitations. In two-dimensional (2D) material heterostructures, charge transfer phenomena play important roles in enabling novel quantum phases, proximity effects, and tunable plasmonic responses. One representative charge transfer interface is formed between α-RuCl3, a van der Waals material with high electron affinity, and graphene. Significant charge transfer across this interface induces the formation of charge-transfer plasmon polaritons (CPPs), hybrid excitations between light and charge oscillations. However, previous studies found that as the charge transfer process takes place, α-RuCl3 becomes lossy, which limits the quality factor of CPPs. Here, we investigate CPPs down to 10 K using a home-built scattering-type scanning near-field optical microscope (s-SNOM) optimized for low-temperature measurements. Our study reveals a dramatic suppression of plasmon loss channels below 40 K, contributing to a significant enhancement in the plasmonic quality factor. This reduction in loss is likely attributed to the blue shift of the correlation-induced Mott gap in α-RuCl3 with decreasing temperature, along with the reduction of phonon scattering at low temperature. Our results highlight the potential of using s-SNOM and CPPs to study complex 2D interfaces and reveal correlated electron dynamics in the underlying material.
Authors
- Mengkun Liu (ORCID: https://orcid.org/0000-0002-3512-9133)
- Yinan Dong (ORCID: https://orcid.org/0000-0002-5996-642X)
- Erdong Song (ORCID: https://orcid.org/0000-0003-1780-2619)
- Lukas Wehmeier (ORCID: https://orcid.org/0000-0001-8416-953X)
- Zijian Zhou (ORCID: https://orcid.org/0000-0003-2383-8490)
- Erik Henriksen (ORCID: https://orcid.org/0000-0002-4978-2440)
- Ran Jing (ORCID: https://orcid.org/0000-0002-0358-6831)
- David Mandrus (ORCID: https://orcid.org/0000-0003-3616-7104)
- Matthew Cothrine (ORCID: https://orcid.org/0000-0001-9026-0241)
- Bing Cheng (ORCID: https://orcid.org/0000-0002-2646-6664)
- Xu Du (ORCID: https://orcid.org/0000-0001-5610-2338)
- G. L. Carr
- Xinzhong Chen (ORCID: https://orcid.org/0000-0002-6103-3848)
- Wenjun Zheng (ORCID: https://orcid.org/0009-0000-0380-8329)
- Jiacheng Sun (ORCID: https://orcid.org/0000-0001-5289-3451)
- Boyi Zhou (ORCID: https://orcid.org/0000-0002-3560-4571)
- D. N. Basov
- Heng Wang (ORCID: https://orcid.org/0000-0003-1030-2873)
Institutions
- Oak Ridge National Laboratory (US)
- Brookhaven National Laboratory (US)
- Washington University in St. Louis (US)
- Stanford Synchrotron Radiation Lightsource (US)
- Yukhnovskii Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine (UA)
- Quantum Leap Innovations (United States) (US)
- National Synchrotron Light Source II
- Stony Brook University (US)
- University of Tennessee at Knoxville (US)
- Columbia University (US)
Publication Details
- Journal
- ACS Photonics
- Published
- 2025-06-06
- DOI
- https://doi.org/10.1021/acsphotonics.5c00296
- Primary Topic
- Graphene research and applications
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Science Foundation
- Gordon and Betty Moore Foundation
- Office of Science
- Basic Energy Sciences