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Presentation: Self-generated electron glasses in frustrated organic crystals

This are the Powerpoint slides of a talk that I gave at the Washington University in St. Louis, and later at the Lorentz Institute, Leiden University, The Netherlands. The abstract was:

Glass, like ordinary window glass, is known for thousands of years, yet it lacks a universal physical description. We do know that unlike normal phases of matter – think of gas, liquid, solids – a glass cannot reach its state of lowest free energy. This is due to a loss of ergodicity, and can also happen in a many-electron system. Usually electron glasses are considered in the presence of disorder, yet last year it was shown that a group of clean organic crystals (known as theta-(BEDT-TTF)_2MM’-(SCN)_4 with M=Tl,Rb,Cs and M’=Co,Zn) also display glassy behavior. We will discuss those results, including the Arrhenius behavior of the relaxation time. After that, we will explain the self-generated glassy physics in terms of frustration arising from the triangular lattice and the Coulomb interaction between the electrons. Mean field theory, exact diagonalization and Monte Carlo simulations provide a quantitative picture of this particular clean electron glass.

Download the powerpoint file (6MB) here: Triangular Glasses

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Poster@Veldhoven2013 and MagLab Winter School

In January 2013 I managed to be at two places at the same time: in FOM Veldhoven and at the Winter School in the National High Magnetic Field Laboratory in Tallahassee, FL, USA. Okay, to be honest: I was physically in Florida, whilst Robert-Jan and Kai made sure my poster was presented in Veldhoven. Thanks guys!

The poster, entitled “Exciton condensation in strongly correlated electron bilayers“, can de downloaded here (PDF, 4.4 MB).

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Poster Physics@FOM Veldhoven 2012

At this years edition of the annual Dutch Physics@FOM conference in Veldhoven I will present a poster entitled “Exciton condensation in strongly correlated electron bilayers“. Actually, for the first time the poster will actually be about exciton condensation, the initial goal of my PhD research.

In the picture here you see an excerpt from the poster, explaining the exciton t-J model Hamiltonian. The poster itself can be downloaded here (pdf, 1.3 MB).

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Poster at NSPM 2011, Erice (and OECS12)

In Erice (a beautiful place in Sicily, Italy) both a summer school and a workshop was held about “Quantum Phenomena in Graphene, other Low-Dimensional Materials, and Optical Lattices“. Needless to say I was there for the “other low-dimensional materials”, with lectures on bilayer exciton condensation (by Allan MacDonald) and oxide heterostructures. At the workshop part I presented a poster on my latest work on excitons in bilayer quantum antiferromagnets, which you of course can download here.


Poster title: Dynamical frustration of interlayer excitons in bilayer quantum antiferromagnets (PDF, 397 kB)

In addition, I discovered that Shou-Cheng Zhang used the picture Jeroen Huijben made for me in his presentation of topological insulators. Zhang’s presentation (amongst others) can be downloaded here.

Update: I presented this very same poster at the international conference on Optics of Excitons in Confined Systems (OECS12) in Paris, 12-16 September 2011.

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Physics@FOM Veldhoven 2010 / Lorentz Workshop April 2011 Poster

At the Physics@FOM Veldhoven 2010 (January 19, 2010) conference I presented a poster with the title “How a Neutral and Massless Superfluid can still exhibit Flux Quantization” (pdf, 2.8 MB).

Image: In concentric bilayers a supercurrent of excitons will exhibit a quantization of the flux in between the two cylinders. The magnetic field lines are shown in red. (Figure made by Jeroen Huijben.)

Update, March 12, 2010: Recently we found that the results, as presented in Veldhoven, were not completely correct. Flux quantization does appear in exciton double layers, however, the trapped flux must be a multiple of $latex \frac{h}{e} \chi_m$ where $latex \chi_m$ is the diamagnetic susceptibility of the exciton double layer.

Update, April 4, 2011: At the Lorentz workshop ‘100th Anniversary of Superconductivity’ I presented a corrected version of the poster. The results have by now been peer-reviewed and published in PRB. On this website I replaced the incorrect old version with the new correct version!