Low-temperature near-field microscope (LT-SNOM)

• Subject Area: Condensed Matter Physics
• Term: Funded in 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 455095592

The applied for low-temperature near-field microscope allows to record near-field optical spectra in the range of THz, infrared and optical frequencies in the temperature regime between 10 and 300 Kelvin with a lateral resolution between 10 and 50 nm. This resolution is significantly below the diffraction limit, and thus allows unprecedented experimental progress. To this end additionally to the main instrument, a THz-spectroscopy system, a CO2 laser source as well as an infrared spectrometer are applied for. For the infrared spectroscopy, we will additionally require an infrared broadband source, which can be used from the room-temperature near-field microscope we are applying for in parallel. The funding possibility for this instrument has been granted in the framework of the basic funding for the call of Prof. Weitz to Göttingen, and is an essential tool for the building up of the group. With the microscope, we will be able to perform various highly innovative experiments in the area of modern solid-state research. For example, we will be able to perform unique investigations in the field of organic electronics. Specifically, we will firstly be able to locally visualize the temperature dependence of the THz conductivity of individual polymer fibers and low-molecular films with nm resolution. This will add significant understanding to the theory of charge-transport mechanisms. Additionally, we will use the unique capability of local infrared spectroscopy to detect the electrical degradation of organic semiconductors as function of temperature. With the as-established methods, we will additionally add basic understanding towards the conductivity of novel metalorganic frameworks. For the area of van-der-Waals materials the applied-for instrument will be additionally extremely important, as it will allow unique understanding of e.g. novel superconductive phases. To this end, we will use lateral mapping of the temperature dependent local conductivity in the infrared with a lateral resolution of below 10 nm to potentially firstly detect the appearance of local superconductive phases e.g in rhombohedral multilayer graphene. Additionally we will firstly be able to trace the temperature dependence of topologically protected states in bilayer graphene or in heterostructures composed of novel two-dimensional polymers and graphene. This unique instrument will additionally allow unique insights into the local appearance of phase transitions in strongly-correlated oxides and charge-density materials as function of temperature.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Tieftemperatur Nahfeldmikroskop (LT-SNOM)
• Instrumentation Group: 5091 Rasterkraft-Mikroskope
• Applicant Institution: Georg-August-Universität Göttingen
• Leader: Professor Dr. R. Thomas Weitz