interlayer plasmon polarons
interlayer plasmon polarons

Discovery of interlayer plasmon polarons in Graphene/WS2 Heterostructures

The discovery of graphene and other two-dimensional (2D) materials ignited considerable efforts to create novel electronic devices from stacked layered materials. Despite being weakly bound by van der Waals forces, these layers can significantly influence each other through long-range Coulomb interactions. Understanding the effects of such interlayer interactions is crucial for designing new low-dimensional devices. In collaboration, scientists from the Institute for Molecules and Materials (IMM) of Radboud University, Aarhus University (Denmark), Carnegie Mellon University (Pittsburgh, USA), E. O. Lawrence Berkeley National Laboratory (Berkeley, USA) and Naval Research laboratory (Washington, USA) revealed that the presence of a single graphene layer can significantly alter the electronic properties of WS2 through interlayer Coulomb interactions. Their findings have recently been published in Nature Communications.

The team studied a heterostructure made of a transition metal dichalcogenide (WS2) and graphene. This combination is commonly used in modern device architectures. The goal was to understand how the properties of the WS2 layer are affected by the presence of the graphene layer.

Plasmon polarons in graphene/ WS2 heterostructures

Angle-resolved photoemission spectroscopy (ARPES) results on the WS2/graphene heterostructure showed specific features  indicating the presence of 'plasmon polaron' quasiparticles. These are electrons that move together with collective oscillations of all the other electrons. These quasiparticles were not found in  WS2 alone, suggesting that the interaction between  WS2 and graphene is crucial. Theoretical models from Yann in ’t Veld and Malte Rösner indicate that, due to long-range Coulomb interactions between the layers, the electrons in the heterostructure oscillate collectively rather than as separately. “This means we could efficiently tune the  WS2 electronical properties via many-body interactions by changing the doping in the graphene layer”, researcher Malte Rösner says. 

Innovative functionalities in nanoelectronics

The implications of this research are profound, offering a pathway to externally tune material properties. “Our work shows that when working with atomically thin layers, you often cannot understand the layers as independent materials and instead need to consider the heterostructure as a whole. This is crucial for the design of novel devices, as interlayer effects can significantly alter conduction properties. Our results also show that understanding interlayer interactions allows for external tuning of material properties, which is one of the requirements for creating atomically thin transistors”, Rösner says.

In future studies, the research team aims to explore how interlayer interactions influence other phases of matter, such as superconductivity, potentially leading to advancing material science and technology.

Literature reference

Observation of interlayer plasmon polaron in graphene/WS2 heterostructures
Søren Ulstrup, Yann in ’t Veld, Jill A. Miwa, Alfred J. H. Jones, Kathleen M. McCreary, Jeremy T. Robinson, Berend T. Jonker, Simranjeet Singh, Roland J. Koch, Eli Rotenberg, Aaron Bostwick, Chris Jozwiak, Malte Rösner & Jyoti Katoch
Nature Communications volume 15, Article number: 3845 (2024)

Contact information

Malte Rösner, m.roesner [at]
Yann in 't Veld, yann.intveld [at]

Innovation, Molecules and materials, Laws of nature, Science