Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 47: Focus Session: Atomic-Scale Studies of Spins on Surfaces with Scanning Tunneling Microscopy 1

O 47.10: Talk

Wednesday, September 7, 2022, 17:45–18:00, S051

A home-built scanning tunneling microscope combined with electron spin resonance — •Andreas Heinrich — Center for Quantum Nanoscience, Institute for Basic Science, Seoul, Korea

Scanning tunneling microscopy is a powerful tool to characterize the electronic and magnetic properties of atomic scale structures on a surface. Recently, improved spectral energy resolution has been achieved by functionalizing the STM tip with a well-characterized molecule at the apex [1,2] or by combining electron spin resonance with STM (ESR-STM) [3]. Here, we present the design and operation of an optimized, home-built ESR-STM with a specially designed mechanical damper, a Joule-Thomson refrigerator, and 2-axes vector magnets. This system provides outstanding performance of STM for nanoscale measurements. We further describe a new design of a microwave antenna to increase the transmission of RF voltages to the junction, which performs better than the direct connection to the tip. Applying RF power through the antenna terminated at 50 Ohm results in the reduction of standing waves and increases the available frequency range (5-40 GHz), which allows us to measure ESR of surface spins at elevated temperatures up to 10 K. References: [1] M. Ormaza et al., Nano let. 17, 1877-1882 (2017) [2] G. Czap et al., Science, 364, 670-673 (2019) [3] S. Baumann et al., Science, 350, 417-420 (2015)