Events at Physics |
Events on Wednesday, December 18th, 2024
- Academic Calendar
- Exams
- Abstract: *Note: actual end time may vary.*
- Thesis Defense
- Developing Josephson Junction Microwave Spectroscopy as a Modality Compatible with Scanned Probe Microscopy at LHe Temperatures
- Time: 2:00 pm - 4:00 pm
- Place: Chamberlin 5280
- Speaker: Margaret Fortman, Physics PhD Graduate Student
- Abstract: Developing new diagnostic tools to understand superconducting surface impurities is crucial for the future of quantum superconducting circuity as well as probing new emergent states in condensed matter. Josephson junction spectroscopy (JJS) in a scanned geometry offers a way to probe defects in superconductors directly, while also correlating their electronic and spatial properties. In this work we show advances towards implementing JJS in a scanning tunneling microscope (STM), where the Josephson junction is created between the superconducting tip and superconducting sample. We first present a way to perform this measurement in an STM by creating a new type of tip that leverages the HF filtering properties of a large tip-sample capacitance design. To demonstrate the benefit of this approach, we then show how a large cross junction capacitance improves performance at elevated temperatures using fabricated Nb-based Josephson junction devices. We also discuss the development of iron selenide as a promising superconducting surface on which to implement this technique. Lastly, we present promising results of our high capacitance STM tip showing its ability to decrease thermal noise and P(E)-broadening and discuss future possibilities of this tool.
- Host: Victor Brar