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

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 3 He 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 = 5 K KeywordsSpin polarized scanning tunneling microscopy Superconducting gap Magnetic structure _____________________________ 1. Electronic

Dense rotational twins in superconducting (111)-orientated δ-NbN epitaxial films on 4H-SiC substrates

“…The critical temperature T C is defined as the temperature with 50% drop of normal state resistivity, R N = R 20K , and the transition width ∆T is the temperature range where the resistivity drops from 0.9R N to 0.1R N . The superconducting energy gap is measured by a homemade 3 He fridge-based scanning tunneling microscope (STM) [48].…”

Topological surface states and superconductivity in non-centrosymmetric PbTaSe2

“…Our STM experiments were performed with our homebuilt ultra-high vacuum (UHV) low-temperature STM 71) and we used electrochemically etched tungsten tips for the STM measurements. PbTaSe 2 single crystals were first cooled below T ∼ 20 K before being mechanically cleaved in situ in cryogenic and UHV environment.…”

Removing background and estimating a unit height of atomic steps from a scanning probe microscopy image using a statistical model

“…To find an appropriate range of the concentration parameter κ for the estimation of µ (1) defined in Eq. (17). The models are the same as those of (a) and (d), respectively.…”

“…We find that the unit height is estimated to be 0.205 ± 0.001 nm. The high precision at the order of a picometer indicates that our method can take advantage of the ultra-low mechanical noise of the state-of-the-art scanning tunneling microscopes [8][9][10][11][12][13][14][15][16][17] .…”