The Microscope that Makes Magnetism Visible
An Unusual Research Instrument
Cobalt, iron and nickel alloys look exactly the same to the ordinary observer. Even under the microscope, at least the type of microscope used in biology class at school. But there are alternatives. For example, a microscope that works using X-ray radiation: such microscopes enable researchers to see structures that are 1000 times smaller, and also to differentiate between materials. “Seeing is understanding,” says Andreas Schümmer, a doctoral student at the Department of Engineering Physics of Münster University of Applied Sciences. This is why he developed such a microscope, which has another great property: it makes magnetism visible.
To do this, it exploits a special feature of the reflection of X-ray radiation on magnetic materials. “I conduct research into nanomaterials for data storage. Computers have to read data, i.e. bits, on their hard disks, which are stored magnetically. This new microscope can be used to find out the exact composition and structure of a sample, and which elements really cause magnetism and magnetic properties.”
Schümmer has already spent three-and-a-half years working on this project. The new microscope now works, and is housed at DELTA (Dortmund electron accelerator) in Dortmund. Electron accelerators are also called synchrotrons, because only they are able to produce a special kind of radiation that Schümmer needs for analysing samples under the microscope: synchrotron radiation. Synchrotron radiation is very intense, and even more powerful than solar radiation – going beyond the UV and X-ray range. The synchrotron therefore resembles a universal, oversized lamp. “The microscope focuses this very radiation onto a small area – in our case, the sample under the microscope,” Schümmer explains.
The microscope stands in a large vacuum chamber. The microscope itself is actually quite small: slightly larger than a shoe box where lots of tiny components are connected up inside. “The most important component is the lens, measuring only 0.23 millimetres. We manufactured it in the cleanroom in cooperation with Forschungszentrum Jülich. It focuses radiation onto the sample in a focal point that’s five times smaller than the diameter of a hair,” Schümmer reports.
Something this size is virtually imperceptible to the human eye – putting together the device is a complex task requiring a great deal of patience and finesse.
Schümmer had the individual components made at the Steinfurt Campus of Münster University of Applied Sciences; he also designed the exact structure of the microscope, and wrote the accompanying software in collaboration with a Bachelor’s degree graduate. It offers a wide range of mechanisms such as nano-motors, which are used to set up and position the sample. “There are possibly a mere handful of X-ray microscopes like this around the world,” Schümmer reckons. He is currently writing his PhD thesis, and takes interested individuals on tours of the DELTA synchrotron.