Functional Materials

Our research has two core themes:

Electromechanical interactions, in particular how residual strains created by defects such as vacancies, dislocations, inclusions and grain boundaries can locally augment polar ordering and electronic structure. Furthermore, we study the manner in which these defects and their concomitant strain fields impede or facilitate the dynamics of interfaces (e.g. domain walls or phase fronts). Our novel synchrotron and FEL-based x-ray microscopy methods provide unique capabilities for imaging morphological and electromechanical phenomena in situ and at unprecedented length and time scales. We often complement these experimental studies with multi-scale simulations based on micromechanical and thermodynamic (e.g. phase-field) approaches.

Coherent x-ray diffraction microscopy, which we use as our primary tool for mapping nanoscale structure-property correlations in embedded sample volumes. Our research addresses all areas of the technique development, from wave optics and phase-recovery algorithms to the design of instrumentation and ensuing data analysis. The majority of our experiments are carried out at international large-scale facilities, such as the European Synchrotron and the European XFEL, however we also have significant laboratory-based activities including visible light, electron and scanning-probe microscopy.

Recent publications:

H. Simons, A.C. Jakobsen, S.R. Ahl, H.F. Poulsen, W. Pantleon, C. Detlefs, Y.-H. Chu, V. Nagarajan, “Non-destructive mapping of long-range dislocation strain fields in an epitaxial complex metal oxide”, Nano Letters 19(3), 1445-1450, (2019) https://doi.org/10.1021/acs.nanolett.8b03839

H. Simons, A.B. Haugen, A.C. Jakobsen, S. Schmidt, F. Stöhr, M. Majkut, C. Detlefs, J.E. Daniels, D. Damjanovic, H.F. Poulsen, “Long-range symmetry breaking in embedded ferroelectrics”, Nature Materials 17(9), 814 (2018). https://doi.org/10.1038/s41563-018-0116-3

H. Simons, A.C. Jakobsen, S.R. Ahl, C.Detlefs, H.F. Poulsen, “Multi-scale characterization with dark-field x-ray microscopy”, MRS Bulletin 41(6) 454-459 (2016) https://doi.org/10.1557/mrs.2016.114

H. Simons, A. King, W. Ludwig, C. Detlefs, W. Pantleon, S. Schmidt, F. Stöhr, I. Snigireva, A. Snigirev, H.F. Poulsen, “Dark field x-ray microscopy for multiscale structural characterization”, Nature Communications 6, 6098 (2015). https://doi.org/10.1038/ncomms7098

Contact

Hugh Simons
Associate Professor
DTU Physics
+45 22 75 51 45