Our group approaches numerous problems in physics and chemistry, utilizing or innovating new state of the art methods in scanning probe microscopy (SPM). Our aim is to understand fundamental problems ultimately toward innovating new approaches to technological applications based on materials science. Our expertise focuses on high precision magnetic and electronic imaging in cryogenic ultrahigh vacuum environments in magnetic fields, often combined with atomic manipulation.

Complex magnetism on surfaces


Spin spiral network in 2ML Fe/Ir(111) [4].

We are interested in surface magnetism beyond the collinear limit, and how interface-driven interactions can lead to new complex magnetic phases of matter, for example skyrmionic or chiral spin order.

Single atom and single molecule magnetism


Spin excitations of individual Fe atoms on Pt(111), measured at T = 30mK, in magnetic field [5].

Our interest is on how utilizing single magnetic atoms and molecules as memory elements, for information technology. Of keen interest is how the magnetic properties, both the static and dynamic behavior of a spin, are modified by environmental effects, such as magnetic anisotropy or ligand fields.

van der Waals materials


Top: Defects on a black phosphorus surface [1] and, bottom: Single-layer MoS2/Au(111) [2].

We are particularly interested in understand interesting electronic and magnetic phases in van der Waal materials, and the role of atomic scale defects or impurities. Moreover, we are interested in van der Waals materials approaching the single layer limit, and the changes to electronic screening in these environments.

Brain-inspired computing


Schematic of the energy landscape differences between bistable memory, and the energy landscapes of interest for brain-inspired hardware

We are interested in utilizing the control we have of individual spin states as well as coupling between atomic spins, as a platform to investigate various types of brain-inspired computing concepts.

Artificial quantum matter: atom-by-atom


Experimental (left) versus calculated (right) spectroscopic map of an artificial Lieb lattice formed by CO molecules on a Cu(111) surface – here highlighting the p-like character of certain bands [3].

We utilize surfaces combined with patterned atomic impurities as a platform to create electronic and magnetic artificial lattices. For example, with this method, we can utilize these platforms as a testbed to realize new states of matter, often not easily realized in crystals, as well as test many cutting-edge theories about the electronic and magnetic behavior, in these limits.

Single molecule light emission


STM-induced light emission allows for combining structural analysis with electronic and optical spectroscopy with sub-molecular resolution, e.g. to study phosphorescent complexes [6].

We apply tunneling-induced light emission detection combined with STM and STS to probe the luminescence behavior of individual molecules on surfaces. We are particularly interested in intra- and intermolecular interactions and how these modify the light emission, toward ultimately creating robust single molecule and aggregated emitters.


  1. Bruix, J. A. Miwa, N. Hauptmann, D. Wegner, S. Ulstrup, S. S. Grønborg, C. E.Sanders, M. Dendzik, A. Grubišić Čabo, M. Bianchi, J. V. Lauritsen, A. A. Khajetoorians, B. Hammer and P. Hofmann, Single-layer MoS2 on Au(111): Band gap renormalization and substrate interaction, Physical Review B 93, 165422 (2016).
  2. B. Kiraly, N. Hauptmann, A. N. Rudenko, M. I. Katsnelson, A. A. Khajetoorians, Probing Single Vacancies in Black Phosphorus at the Atomic Level. Nano Letters17, 3607-3612 (2017).
  3. M. R. Slot, S. N. Kempkes, E. J. Knol, W. M. J. van Weerdenburg, J. J. van den Broeke, D. Wegner, D. Vanmaekelbergh, A. A. Khajetoorians, C. M. Smith, and I. Swart, p-Band Engineering in Artificial Electronic Lattices, Physical  Review X 9, 011009 (2019).
  4. N. Hauptmann, M. Dupé, T.-C. Hung, A. K. Lemmens, D. Wegner, B. Dupé, and A. Khajetoorians, Revealing the correlation between real-space structure and chiral magnetic order at the atomic scale, Physical Review B97, 100401(R) (2018).
  5. H. v. Allwörden, A. Eich, E. J. Knol, J. Hermenau, A. Sonntag, J. W. Gerritsen, D. Wegner, A. A. Khajetoorians, Design and performance of an ultra-high vacuum spin-polarized scanning tunneling microscope operating at 30 mK and in a vector magnetic field. Review of Scientific Instruments89, 033902 (2018).
  6. J. Sanning, P. R. Ewen, L. Stegemann, J. Schmidt, C. G. Daniliuc, T. Koch, N. L. Doltsinis, D. Wegner and C. A. Strassert, Scanning-Tunneling-Spectroscopy-Directed Design of Tailored Deep-Blue Emitters, Angewandte Chemie Int. Ed. 54, 786 (2015).