A Millikelvin Scanned Probe for Measurement of Nanostructures

TL;DR

This paper presents a novel millikelvin scanning probe microscope based on a quartz tuning fork, capable of high-resolution imaging and electrical measurements of nanostructures at ultra-low temperatures and high magnetic fields.

Contribution

It introduces a cryogenic scanning probe with integrated electrical probing and low noise amplification, enabling detailed nanostructure analysis at millikelvin temperatures.

Findings

Imaging resolution below 1 micron at millikelvin temperatures.

Successful measurement of Coulomb blockade with high sensitivity.

Operates effectively in magnetic fields up to 6 Tesla.

Abstract

We demonstrate a scanning force microscope, based upon a quartz tuning fork, that operates below 100 mK and in magnetic fields up to 6 T. The microscope has a conducting tip for electrical probing of nanostructures of interest, and it incorporates a low noise cryogenic amplifier to measure both the vibrations of the tuning fork and the electrical signals from the nanostructures. At millikelvin temperatures the imaging resolution is below 1 um in a 22 um x 22 um range, and a coarse motion provides translations of a few mm. This scanned probe is useful for high bandwidth measurement of many high impedance nanostructures on a single sample. We show data locating an SET within an array and measure its coulomb blockade with a sensitivity of 2.6 x 10^-5 e/Hz^1/2.