Quantum Electron Matter van der Waals-Zeeman Institute

Singular Physics of 1D Electrons: STM/STS and ARPES of gold nanowires.

The research performed in our group will focus on self assembled metallic nanowires on the Ge(001) surface. At this point we are still developing the tools to grow self-assemblednanowires. In the near future we will be able to grow nanowires in situ in our STM and ARPES setups. Once we have explored the parameters affecting the formation of nanowires we will collaborate with the ESCHER group at the University of Leiden to study 1D physics using the PEEM setup. read more

ARPES and STM/STS on the new iron pnictide high Tc superconductors

The aim of this research is to reach a better understanding of the physics driving the superconductivity in these iron pnictide and related systems. Our approach is to combine the forces of scanning tunneling microscopy and spectroscopy (STM/STS), hard x-ray photoemission (HAXPES), angle resolved photoemission (ARPES) and optics measurements, all carried out on the same high-quality single crystals grown in our own crystal lab by Dr. Yinkai Huang (mostly via a self-flux technique). read more

Topological Insulators

Topological insulators are one of the hot topics in condensed matter physics. These are materials that are (ideally) insulating in the bulk of the material, but have metallic surfaces. The presence of conducting surface states in insulators is nothing new, but in the recently discovered alloys BiSb, Bi2Se3, Bi2Te3 and some intercalated versions of these materials the surface states are robust against the effects of impurity scattering on adatoms at the surface. read more

XPS on oxide heterointerfaces

In 2004 Ohtomo and Hwang discovered that conductivity arises at the interface between TiO2 terminated SrTiO3 (STO) and LaAlO3 (LAO), two non conducting oxides. Later it was found that these interfaces not only conduct but can show signs of superconductivity and magnetism as well. The conductivity is suspected to be localised in a thin layer around the interface in a two dimensional electron gas (2DEG). The origin of this 2DEG is still under debate. read more

Strongly correlated electron systems: 'strange' metals and the new FM superconductor UCoGe

The problem of the formation of a strongly correlated electron state in intermetallics, oxides and organic materials, is one of the major issues in solid-state physics. We focus on cerium and uranium intermetallics, where a unique renormalization of the thermodynamic electron mass of the order of 100 to 1000 times the free electron mass is found. These materials, termed heavy-fermion or heavy-electron compounds, serve as exemplary systems to study electron renormalization phenomena within the Fermi-liquid scenario. read more

ARPES and STM on giant magnetoresistant manganites

One of the major challenges of contemporary physics is to gain insight into many-body problems such as high temperature superconductivity displayed by e.g. various cuprates. A similar group of materials are the manganites that display an equally poorly understood phenomenon. Combined ARPES and STM studies will lead to a better understanding of these materials. read more

Magnetic domains studied with novel resonant x-ray techniques

Our research aims at utilizing new x-ray magneto-optical methods for the study of thin magnetic films and nanometric magnetic devices. We use magnetic stripe domains in amorphous rare-earth transition-metal films as a test bed for x-ray resonant magnetic scattering and x-ray resonant microscopy studies. The engineering of the domain structure by means of focused ion beams is explored. Recently we also managed to measure the slow dynamics of antiferromagnetic domains in an ultrathin Ho film via resonant x-ray photon correlation spectroscopy. read more

Low-dimensional electron systems

  Electron systems with reduced dimensionality have opened the prospect to study in great detail a wide range of physical phenomena, like weak and strong carrier localization, quantum interference effects, the quantum Hall effect, quantum confinement of carriers and charge quantization. These phenomena allow for unprecedented studies of electronic parameters, like (in)elastic electron scattering rates, the phase relaxation time of the electron wave function, Coulomb interactions, etc. We envisage to study a number of these effects in (quasi-)two and one-dimensional electron systems, with a special effort on magnetic quantum oscillations in very strong magnetic fields and low temperatures. read more