New directions in point-contact spectroscopy based on scanning tunneling microscopy techniques (Review Article)

Abstract

Igor Yanson showed 38 years ago for the first time a point-contact measurement where he probed the energy resolved spectroscopy of the electronic scattering inside the metal. Since this first measurement, the pointcontact spectroscopy (PCS) technique improved enormously. The application of the scanning probe microscopy (SPM) techniques in the late 1980s allowed achieving contacts with a diameter of a single atom. With the introduction of the mechanically controlled break junction technique, even spectroscopy on freely suspended chains of atoms could be performed. In this paper, we briefly review the current developments of PCS and show recent experiments in advanced scanning PCS based on SPM techniques. We describe some results obtained with both needle-anvil type of point contacts and scanning tunneling microscopy (STM). We also show our first attempt to lift up with a STM a chain of single gold atoms from a Au(110) surface.

Atomic resolution scanning tunneling microscopy in a cryogen free dilution refrigerator at 15 mK

“…For these experiments we used an STM head built in-house similar to other setups used previously at low temperatures 5,20 . The STM is based on the Pan walker design 3,21 .…”

Intuitive human interface to a scanning tunnelling microscope: observation of parity oscillations for a single atomic chain

“…In this section we will show how the above system with the real-time MD simulation works using some simple lateral manipulation test followed by an experiment where we lifted a chain of Au atoms out of the surface in a controlled manner forming a free-standing atomic chain between the tip and the sample. Some challenges in creating such a free-standing atomic chain using a controlled STM technique are addressed by Tartaglini and co-workers [29]. These atomic chains are ideal one-dimensional (1D) systems and are known to be formed only in pure metals such as Au, Pt and Ir.…”

Nano-contact microscopy of supracrystals

“…The possibility of atomic scale point-contact imaging in STM was recognised by Smith et al almost three decades ago [ 22 ], and in the intervening years, the relationship between the variation in the tunnel current and the tip–sample force as a function of probe displacement has been studied in considerable detail [ 23 – 27 ]. A recent review [ 28 ] outlines key developments in point-contact measurements, including the quantum point-contact microscopy strategy introduced by Zhang et al [ 29 ]. State-of-the-art qPlus DFM, where both intra- [ 30 – 31 ] and inter-molecular [ 32 – 34 ] resolution are increasingly the norm, also exploits imaging in the point-contact regime for which electron repulsion underpins the contrast mechanism (as pioneered by Gross et al [ 30 ]).…”