The design and the performance of an ultrahigh vacuum 3He fridge-based scanning tunneling microscope with a double deck sample stage for in-situ tip treatment

TL;DR

This paper details the development of an ultrahigh vacuum 3He fridge-based STM with a double deck sample stage, enabling in-situ tip treatment and high-resolution imaging of magnetic order at millikelvin temperatures.

Contribution

It introduces a novel STM design that allows in-situ tip and sample preparation, enhancing capabilities for low-temperature, high-magnetic-field atomic-scale studies.

Findings

Achieved an energy resolution of 400 mK at 310 mK.

Successfully imaged magnetic order in FeTe at 5K.

Demonstrated in-situ tip cleaning and preparation capabilities.

Abstract

Scanning tunneling microscope (STM) is a powerful tool for studying the structural and electronic properties of materials at the atomic scale. The combination of low temperature and high magnetic field for STM and related spectroscopy techniques allows us to investigate the novel physical properties of materials at these extreme conditions with high energy resolution. Here, we present the construction and the performance of an ultrahigh vacuum 3He fridge-based STM system with a 7 Tesla superconducting magnet. It features a double deck sample stage on the STM head so we can clean the tip by field emission or prepare a spin-polarized tip in situ without removing the sample from the STM. It is also capable of in situ sample and tip exchange and preparation. The energy resolution of scanning tunneling spectroscopy at T = 310 mK is determined to be 400 mK by measuring the superconducting gap with a niobium tip on a gold surface. We demonstrate the performance of this STM system by imaging the bicollinear magnetic order of $Fe_{1+x}Te$ at T=5K.