In the Golden lab - part of the QMat group - spectroscopic tools are used to investigate the electronic structure and properties of emergent and strongly correlated quantum matter systems. These include, complex oxides and their (hetero)interfaces, topological insulators and unconventional superconductors. Our experimental techniques of choice are direct probes of the electronic structure such as angle-resolved photoemission, soft X-ray absorption, dichroism and scattering, hard x-ray photoemission and STM/STS. To enable these studies, we grow our own high-quality single-crystals of these materials (Dr. Yingkai Huang), fabricate our own 1D nanostructures using surface physics methods in ultrahigh vacuum and collaborate with leading thin film growth laboratories, both in the Netherlands and abroad.
Working on tomorrow's materials today
The systems we work on are at the forefront of fundamental solid state physics research, but also possess potential for eventual application in future technologies connected to:
- energy (superconductors)
- spintronics (topological insulators, magnetoresistive systems) and
- nanoscience (1D systems, oxide heterointerfaces).
Topological insulators are a new phase of quantum matter in which electronic states enjoy immunity from disorder and possess special properties such as the ability to carry dissipationless spin currents and even host Majorana zero modes. Their special characteristics are intimately connected to their band structure and so the direct probes we use like ARPES and STS are ideal tools with which to study these new systems. Our work focusses on the search for new (three-dimensional) topological materials and in collaboration with the de Visser and van Heumen labs we study TI's using both transport and a variety of spectroscopic techniques. In the person of Mark Golden, QMat leads the FOM-funded, Dutch national research programme 'Topological Insulators', which involves a combination of excellent experimental and theory groups from Amsterdam, Leiden, Delft and Twente.
PhD researchers on this project are: Shyama Varier Ramankutty (Golden lab) and Yu Pan (de Visser lab).
The applications window for a postdoc position in topological insulators is now closing.... - see the 'News' part of the webpage.
Singular physics of 1D wires
The Golden lab is a partner in the FOM-funded, Dutch national research programme called 'The singular physics of 1D electrons' (programme leader Harold Zandvliet [MESA+, Twente]). The main objective of this FOM programme is to realize, investigate, understand and ultimately tailor the physical properties of one‐dimensional (electron) systems. We collaborate intensively with Harold Zandvliet's group on the growth and investigation of self-assembled noble metal nanowires (Au, Pt) on semiconductor surfaces, with theory on 1D systems coming from another programme partner, Jean-Sebastien Caux from the UvA.
The PhD researcher on this project is: Nick de Jong (Golden lab).
The Golden and van Heumen labs, together with our adjunct Prof. colleague Hermann Dürr (based at SIMES in SLAC) are partners in the FOM-funded, Dutch national research programme called '2-dimensional electron systems in complex oxides' (programme leader Hans Hilgenkamp [MESA+, Twente]). This programme is centred around the complex oxide pulsed-laser deposition activities in Twente and bundles Dutch expertise on complex oxide thin film growth, with experiments involving transport, device generation, spectroscopy and high-field studies. QMat is engaged in photoemission spectroscopy and X-ray spectroscopies on samples from the Twente groups (conducted both in the Amsterdam lab and at synchrotron radiation sources), using our jointly developed UHV-suitcase to transfer samples without breaking vacuum. The connection to Hermann's group at SLAC will facilitate advanced soft X-ray experiments aimed at imaging and ultrafast studies.
We have a PhD position open (Golden lab+ collaboration with Dürr group), and the applications window is now closing..... - see the 'News' part of the webpage.
We have a postdoc position open (Golden lab + collaboration with Dürr group) we will shortly be recruiting for on this project - contact us if you are interested.
Unconventional superconductors like those found in the cuprate, iron-pnictide and heavy fermion materials families are examples of emergent states of matter that derive their remarkable properties from the collective behaviour of interacting electrons. Despite the many differences that can be pointed out between these materials, superconductivity always seems to occur near magnetically ordered phases and involve quantum criticality. Using optical spectroscopy, ARPES and STM the van Heumen & Golden labs are searching for smoking-gun evidence of the interactions that underlie the superconducting instabilities. The de Visser lab has a long-standing research programme on heavy Fermion superconductivity.
In addition to the issue of unconventional superconductivity, the 'strange metal' phase found outside the superconducting part of the phase diagramme of these systems is also of great topical interest.
PhD researchers on this project are: Artem Nikitin (de Visser lab) and Alona Tytarenko (van Heumen lab).