Scanning Tunneling Microscope

Scanning Tunneling Microscope (STM）was first developed in 1981 by Gerd Binning and Heinrich Rohrer at the IBM Zurich Research Laboratory, who earned the Nobel Prize in Physics in 1986. STM primarily utilizes quantum tunneling effects to image surfaces of objects. In STM, a sharp metal tip, consisting of only a few atoms at its apex, is brought to within about 1 nanometer of the sample surface. By applying a voltage between the tip and the sample, electrons can tunnel through the vacuum barrier, generating a tiny tunneling current. As the distance between the tip and the sample changes, the tunneling current exponentially varies with the distance, providing picometer-scale spatial resolution. During STM scanning, as the tip moves across the sample surface, measuring changes in this tunneling current allows the mapping of the surface’s topography. 

However, the function of STM goes far beyond imaging surface morphology. It can manipulate and move atomic structures to create specific potential wells, enabling the study of interference and
scattering between electrons. Over the past two decades, technological advancements have allowed us to gather rich electronic state information using STM, such as changes in electronic density at the level of single atoms, vacancies, impurities, interfaces, and domain walls. Furthermore, fluctuations in the density of states across a wide area on the material’s surface provide momentum and phase information about electron wavefunctions. This aids in studying coupling effects between electrons-electrons, electrons-phonons, electron spin-orbit interactions, as well as complex many-body effects like superconductivity, charge density waves, and superconducting pairing density waves. Recently, we’ve begun using topological insulators to prepare tips, enabling the direct study of  electron behavior within the framework of relativistic quantum mechanics, laying the groundwork for developing a new generation of dissipationless and spin devices. Based on STM, our primary
research directions employing STM will focus on the following:

 1. Studying quantum critical
behaviors and their control parameters at the single-atomic scale;

2. The Symmetry of Superconducting Order
Parameters and Pairing Mechanisms;

3. The Fundamental Properties and
Applications of Dirac Electrons in Correlated Topological Materials;

4. Developing and Utilizing Novel Probes
to Study Topological and Quantum Magnets.

 

Unisoku 1500 STM system (base temperature
1.5K; magnetic field: 8T)

 

Unisoku 1600 STM system (base temperature
30mK; magnetic field: 9-2-2T)