Scientific Highlights
Integration of Li4Ti5O12 crystalline films on silicon towards high-rate performance lithionic devices
The growth of crystalline Li-based oxide thin films on silicon substrates is essential for the integration of next-generation solid-state lithionic and electronic devices. In this work, we employ a 2 nm γ-Al2O3 buffer layer on Si substrates in order to grow high quality crystalline thin films Li4Ti5O12 (LTO). Long-term galvanostatic cycling of 50 nm LTO demonstrates exceptional electrochemical performance, specific capacity of 175 mAh g-1 and 56 mAh g-1 at 100C and 5000C respectively, with a capacity retention of 91% after 5000 cycles.
A star is born
Swiss Light Source SLS reveals complex chemistry inside ‘stellar nurseries’
Momentum-resolved electronic structure of LaTiO2N photocatalysts by resonant Soft-X-ray ARPES
Oxynitrides are promising materials for visible light-driven water splitting. However, limited information regarding their electron-momentum resolved electronic structure exists. Here, with the advantage of the enhanced probing depth and chemical state specificity of soft-X-ray ARPES, we determine the electronic structure of the photocatalyst oxynitride LaTiO2N and monitor its evolution as a consequence of the oxygen evolution reaction. After the photoelectrochemical reactions, we observe a partial loss of Ti- and La-N 2p states, distortions surrounding the local environment of titanium atoms and, unexpectedly, an indication of an electron accumulation layer at or near the surface, which may be connected with either a large density of metallic surface states or downward band bending. The distortions and defects associated with the titanium 3d states lead to the trapping of electrons and charge recombination, which is a major limitation for the oxynitride LaTiO2N. The presence of an accumulation layer and its evolution suggests complex mechanisms of the photoelectrochemical reaction, especially in cases where co-catalysts or passivation layers are used.
Advancing the JUNGFRAU detector toward low-energy X-ray applications
“Soft” x-rays are notoriously hard to detect. Particularly, in the context of high-performance synchrotron and free electron laser (FEL) experiments, suitable detector options for low-energy x-rays are highly sought after. Currently available options only provide limited area, readout speed, and dynamic range. Now, a team of scientists from the Laboratory for X-Ray Nanoscience and Technologies (LXN) at PSI are challenging these limitations. They combined a detector made at PSI with newly developed silicon sensors to push the resolution toward the soft x-ray limit. A first version of this detector system is now in operation at the SwissFEL endstation Maloja. And it points to further possibilities to refine the detector technology to eventually catch the elusive soft x-rays.
How to squash things carefully
A new in situ uniaxial pressure cell at Paul Scherrer Institute PSI gives scientists unrivalled control to tweak quantum materials microscopically and tune their properties.
Visualizing Higher-Fold Topology in Chiral Crystals
Novel topological phases of matter are fruitful platforms for the discovery of unconventional electromagnetic phenomena. Higher-fold topology is one example, where the low-energy description goes beyond standard model analogs. Despite intensive experimental studies, conclusive evidence remains elusive for the multigap topological nature of higher-fold chiral fermions. In this Letter, we leverage a combination of fine-tuned chemical engineering and photoemission spectroscopy with photon energy contrast to discover the higher-fold topology of a chiral crystal.
IEEE Early Career Award 2022
For contributions to the development of detectors for XFELs and specifically for their verification, characterization, and calibration
Commissioning of the novel Continuous Angle Multi-energy Analysis spectrometer at the Paul Scherrer Institut
We report on the commissioning results of the cold neutron multiplexing secondary spectrometer CAMEA (Continuous Angle Multi-Energy Analysis) at the Swiss Spallation Neutron Source at the Paul Scherrer Institut, Switzerland. CAMEA is optimized for ...
Simulations on "Piz Daint" explain surprising mineral behaviour
Zeolites are a class of shapely, colourful minerals with very special properties, making them omnipresent in our surroundings. They accelerate chemical reactions, absorb hazardous contaminants and water to a high degree, for example. Their only limitation is that they usually lose their peculiar crystalline structure at high temperatures. Now researchers at the University of Bern have found an unexpected exception.
Discovery of a large unquenched orbital moment in a 2D van der Waals ferromagnet
3d transition metals often exhibit a quenched orbital moment when in a solid state system. Therefore, the proposition of a large unquenched orbital moment for V in VI3 caused some surprise and discussion in the scientific community. Experimental and theoretical works diverge on the fact of whether the orbital moment is quenched or not. In our work we have been able to give an answer this open issue, proposing also a model for the ground state of VI3.