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Our studies primarily focus on the investigation of atoms and molecules at their intrinsic length scales. To this end, most of our microscopes are operated under ultrahigh-vacuum (UHV) and cryogenic temperature (10K and below) conditions. This allows examining single molecules under clean and stable conditions.

Furthermore, all of our microscopes are equipped with the required toolset for in-situ preparation of atomically flat and clean samples.

Combined Scanning Tunneling/Atomic Force Microscopes

These two equivalent setups are based on a qPlus sensor design, which allows us to perform scanning tunneling microscopy (STM) and atomic force microscopy (AFM) measurements simultaneously. Functionalizing the tip with additional atoms or molecules enables the AFM study of intramolecular phenomena with sub-ångstrom precision. These microscopes are also capable of employing the newly developed AC-STM technique, which allows the investigation of molecular orbitals on insulating surfaces.

Lightwave Scanning Tunneling Microscope

One of the most recent developments in a collaboration with the group of Prof. Rupert Huber at the University of Regensburg culminated in the establishment of lightwave scanning tunneling microscopy (LW-STM). Here, phase-stable laser pulses in the terahertz regime are coupled into the tunneling junction, which act as a transient bias voltage. This permits the manipulation of single electrons on a femtosecond time scale and can be used to track the motion of individual molecules with sub-molecular precision.

2K/9T Scanning Tunneling Microscope

The cryostat of this microscope is equipped with a so-called 1K-pot allowing for a sample temperature of slightly below 2 K, while a solenoid magnet can provide magnetic fields of up to 9 T. This combination of temperature and field allows for inelastic spin-flip excitations to be detected in scanning tunneling spectroscopy, such that this microscope is dedicated to spin-related studies.

mK/10T Scanning Tunneling Microscope

Furthermore, we are setting up a scanning tunneling microscope dedicated to reach lowest temperature in a dilution cryostat, while facilitating sample preparation under ultra-high-vacuum conditions. In scanning tunneling spectroscopy, the temperature determines the energy resolution. Hence, the goal of setting up this apparatus is reaching highest resolution and being able to study very-low energy excitations. We aim at reaching temperatures of 50 mK.

Mid Infrared Lightwave Scanning Tunneling Microscope

With this next-generation lightwave-driven scanning tunneling microscope we envision to reach low-fs time scales by driving the tunneling process with sub-cycle mid-infrared laser pulses. The novel microscope head facilitates an integrated optical mirror and a dedicated optical pathway to couple the laser into the cryostat. This development is pursued in a collaboration with the group of Prof. Rupert Huber.

Towards lightwave-driven scanning tunneling microscopy in a magnetic field

Currently, next-generation lightwave-driven scanning tunneling microscopes are being build, in collaboration with the group of Prof. Rupert Huber. In the framework of the collaborative research center 1277 we are establishing lightwave-driven scanning tunneling microscopy in a magnetic field (3T) to study single-spin precession and related phenomena directly in the time domain at the atomic scale.

  1. University
  2. https://www.uni-regensburg.de/rechenzentrum

Repp Group

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Artistic Illustration of ESR-AFM

© Eugenio Vázquez

In a recent publication in Nature, we report on the measurement of electron spin resonance signals with atomic force microscopy.