Achieving μeV tunneling resolution in an in-operando scanning tunneling microscopy, atomic force microscopy, and magnetotransport system for quantum materials research

---

J. Schwenk, S. Kim, J. Berwanger, F. Ghahari, D. Walkup, M.R. Slot, S.T. Le, W.G. Cullen, S.R. Blankenship, S. Vranjkovic, H.J. Hug, Y. Kuk, F.J. Giessibl, J.A. Stroscio,

---

Review of Scientific Instruments

Research in new quantum materials requires multi-mode measurements spanning length scales, correlations
of atomic-scale variables with a macroscopic function, and spectroscopic energy resolution obtainable only at
millikelvin temperatures, typically in a dilution refrigerator. In this article, we describe a multi-mode instrument
achieving a μeV tunneling resolution with in-operando measurement capabilities of scanning tunneling
microscopy, atomic force microscopy, and magnetotransport inside a dilution refrigerator operating at 10 mK.
We describe the system in detail including a new scanning probe microscope module design and sample and
tip transport systems, along with wiring, radio-frequency filtering, and electronics. Extensive benchmarking
measurements were performed using superconductor–insulator–superconductor tunnel junctions, with
Josephson tunneling as a noise metering detector. After extensive testing and optimization, we have achieved
less than 8 μeV instrument resolving capability for tunneling spectroscopy, which is 5–10 times better than
previous instrument reports and comparable to the quantum and thermal limits set by the operating
temperature at 10 mK.

 

https://www.nist.gov/news-events/news/2020/07/atomic-swiss-army-knife-precisely-measures-materials-quantum-computers
https://www.uni-regensburg.de/pressearchiv/pressemitteilung/1076639.html
https://aip.scitation.org/doi/10.1063/5.0005320