Project Details
Projekt
Compressive strain in stacked 2D materials: from proximity to metastable hybridization
Applicant
Professor Dr. Roland Bennewitz
Subject Area
Experimental Condensed Matter Physics
Term
from 2020 to 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 443275141
Two-dimensional (2D) materials are characterized by strong chemical bonds between the atoms in one plane and weak physical bonds between layers. They exhibit high mechanical strength in the plane and are very flexible at the same time. The reduction of the electronic structure to two dimensions leads to many interesting properties such as high carrier mobility in graphene or strong coupling of the electron spin in MoS2. The Schwerpunktprogramm will explore the new physics in stacks of 2D materials, where the proximity of the layers induces collective electronic states. In this project we will explore a new regime of mechanical properties and electrical conductance in stacked layers which are compressed by an external load. With the distance reduced by high pressure, even temporary chemical bonds can form between the layers. This hybridization has an dramatic influence on conduction and mechanical response. We will apply the pressure and probe the material properties by the nanoscale conductive tip of an atomic force microscope. Atomic sensitivity and resolution will be obtained by performing the experiments on very clean samples in ultra-high vacuum. The dynamics of layer-layer interaction will be explored in atomic friction measurements, where sliding velocity and temperature are varied. These experiments track the dissipation arising from the formation of temporary chemical bonds and probe their lifetime. Simultaneously, the changes in the electrical conductance, which are expected for different hybridization, will be measured.Within the SPP, the project will be part of a collaboration towards the preparation of stacked heterostructures of 2D materials in the highest structural quality. The pressure-induced changes in mechanical properties and electrical transport will be investigated in collaboration with theory groups simulating the chemical bonding at the atomic scale. Understanding the impact of compressive strain on stacked 2D materials will help to build novel flexible electronics and to develop pressure-sensitive devices.
DFG Programme
Priority Programmes
