Performance benchmarking of an ultra-low vibration laboratory to host a commercial millikelvin scanning tunnelling microscope

Abstract

Ultra-low temperature scanning tunnelling microscopy and spectroscopy (STM/STS) achieved by dilution refrigeration can provide unrivalled insight into the local electronic structure of quantum materials and atomic-scale quantum systems.
Effective isolation from mechanical vibration and acoustic noise is critical in order to achieve ultimate spatial and energy resolution. Here, we report on the design and performance of an ultra-low vibration (ULV) laboratory hosting a customized but otherwise commercially available 40-mK STM. The design of the vibration isolation consists of a T-shaped concrete mass block (~55t), suspended by actively controlled pneumatic springs, and placed on a foundation separated from the surrounding building in a “room-within-a-room” design. Vibration levels achieved are meeting the VC-M vibration standard at >3 Hz, reached only in a limited number of laboratories worldwide. Measurement of the STM’s junction noise confirms effective vibration isolation en par with custom built STMs in ULV laboratories. In this tailored low-vibration environment, the STM achieves an energy resolution of 43 μeV (144 mK), promising for the investigation and control of quantum matter at atomic length scales.

A Gate‐Tunable Ambipolar Quantum Phase Transition in a Topological Excitonic Insulator

“…[26,28,43,45] While an SOC type different from that assumed in Equation (1) could influence the precise order parameters of the excitons due to the change in the bare band characters, the doping dependence and DOS inferred from our calculations should not have any significant dependence on the SOC type, as long as the resulting bare band dispersion remains similar. Future local probe spectroscopy experiments in magnetic fields and/or with magnetic probes [46] should allow to reveal the CDW, SDW, or spin spiral ground states and thus shed light on the precise SOC type.…”