Scanning tunnelling microscope to investigate quantum materials

• Subject Area: Condensed Matter Physics
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 551550227

With this proposal, Ludwig-Maximilians-Universität (LMU) München requests to purchase a scanning tunnelling microscope (STM). The most intriguing features of quantum materials can often only be studied at very low temperatures, a few degrees above the absolute zero of the temperature scale. Often, local information is key, in part because quantum materials tend to be heterogenous. LMU has recently expanded its experimental solid-state and quantum sensing programs with the hiring of several people, including new Chair of Experimental Physics – Quantum Metrology and Sensing, Prof. Dr. Milan Allan. In this chair, researchers investigate quantum materials with STMs at low temperatures (£ 4.2K). STMs allow the taking of atomic-resolution topographic images of sample surfaces. In spectroscopy mode, STMs can also access the electronic density of states of the material in question, which is often of crucial interest for quantum materials. It is possible to additionally implements different measurement modes, including noise-STM and Josephson-STM. There is a crucial need for an ultra-low temperature (<1K) STM for this research, but there is currently none available at LMU. With this proposal, LMU aims to buy a commercial helium-based low-temperature STM that can be cooled to below 1 Kelvin, has high mechanical stability and a low helium boil-off, and allows the integration of custom STM techniques. The latter requires at least three electrical contacts on the tip side and at least four contacts on the sample side. Further, it should be compact enough to be placed in the most vibration-free rooms at LMU.The new STM will strengthen the experimental solid-state program at LMU. It will allow electron pair microscopy and Josephson-STM to be performed on a wide range of quantum materials and reveal fundamental new insights into Kagome materials, twisted bilayer graphene, and disordered superconductors.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Scanning tunnelling microscope to investigate quantum materials
• Instrumentation Group: 5091 Rasterkraft-Mikroskope
• Applicant Institution: Ludwig-Maximilians-Universität München
• Leader: Professor Milan Allan