“VEKMAG” at BESSY II creates 3D magnetic fields in samples
A general view of the VEKMAG end-station. The vector magnet chamber (grey) is supported by a hexapod frame. Below the magnet one can distinguish the detector chamber (green) and in the forward direction the deposition chamber (dark grey) is displayed. The beam quality is monitored by a diagnostic chamber (yellow) positioned in front of the magnet chamber. © Dr. Tino Noll
Together with HZB, teams from the Universität Regensburg, from the Freie Universität Berlin and from the Ruhr Universität Bochum have jointly set up a unique measurement station at BESSY II: a vector electromagnet consisting of three mutually perpendicular Helmholtz coils which enables setting the local magnetic field at the sample position to any orientation desired. The first measurements of magnetic materials, spin systems, and nanostructured magnetic samples are scheduled for early 2015.
“We have been working on this project for almost six years”, reports HZB physicist Dr. Florin Radu. He is coordinating the project with the three universities. The deposition chamber for the samples was designed at Freie Universität Berlin. Ruhr Universität Bochum built the detector chambers, and Universität Regensburg developed the concepts for synchrotron beam-based ferromagnetic resonance experiments.
Rapid change of polarisation
In the meantime, Radu and his team ensured optimum characteristics of a new beamline for carrying out most sophisticated experiments: “We need an extremely stable beam, but we also want to be able to change the polarisation of the x-rays very rapidly”, he explains. “For that reason, we developed a hexapod vacuum chamber with six moveable legs supporting a mirror. By changing the leg positions slightly, we can change the orientation of the first mirror and thereby the polarisation of the x-ray beam in just seconds – about one hundred times faster than before.” The tests show that this prototype arrangement improves the signal-to-noise ratio by a factor of more than ten.
Temperature between 1,6 K and 500 K
The new experimental station will not only facilitate many different kinds of studies, particularly in the soft X-ray region, but will also permit to carry out completely new studies that require temperatures of 500 Kelvin right down to 1.6 Kelvin and magnetic fields as high as nine tesla. Simultaneously the X-rays can penetrate the individual atoms and excite their outer electrons, enabling magnetic properties of the individual elements to be distinguished.
The main assets of the new VEKMAG end-station are experimental specifications that are unique in comparison with stations operating at other international facilities. In particular for element-specific and time-resolved measurements of ferromagnetic and paramagnetic resonances, as well as for spectroscopic and scattering experiments VEKMAG offers a unique sample environment. However, “VEKMAG will only attain its full potential, once HZB has implemented a new innovative beam filling pattern with variable pulse lengths at full photon intensities”, according to Radu, because “we can then investigate rapid spin dynamics with sub-picosecond time resolutions.”
The VEKMAG project was funded by the German Federal Ministry for Education and Research (BMBF) through a grant of about four million Euros.
- New discoveries into how the body stores zincZinc deficiency is a global health problem affecting many people and results in a weak immune system in adults and especially in children. This is a challenge for health systems and is quite evident in the Mexican population, for example. Seeking explanations, researchers in Mexico teamed up with international synchrotron experts and gained new insights from studying Drosophila fruit flies, which are known to be a decent model system for human zinc metabolism.
Thanks to beamtime at BESSY II and at the SLS (PSI), they were able to show that the zinc stores in Drosophila flies depend on the tryptophan content of their diet. - International consortium to advance decarbonisation of the aviation sectorJOHANNESBURG, SOUTH AFRICA – 24 May 2022: CARE-O-SENE research project will develop advanced catalysts for sustainable aviation fuels
The company Sasol and Helmholtz-Zentrum Berlin (HZB) will lead a consortium to develop and optimise next-generation catalysts that will play a key role in decarbonising the aviation sector through sustainable aviation fuels (SAF).
- Shutdown at BESSY II: new supply technology ensures long-term operationThe X-ray source BESSY II is in a three-month period of shutdown. During this period, the low voltage main distribution panel in the supply building outside the electron storage ring is being renovated. This will secure the long-term operation of BESSY II over the next decade.