Nano-precision metrology of X-ray mirrors

Synchrotrons work like a giant microscope, and they both need mirrors and lenses to bend and shape light. The better control we have over the light source, the more we can see. The quality of images that can be captured using a microscope or a synchrotron rely heavily on the optics used.

As technology has advanced over the past few decades and as synchrotron users push the boundaries of what can be achieved, there has been a lot of excitement over the upgrades of synchrotron mirrors and what that can mean for the experiments that can be done.

However, there is a bottleneck for the production of new and improved X-ray optics like mirrors. It turns out that it is hard to develop metrology instruments that can validate and measure the quality of new high-precision mirrors. Producing these instruments and alleviating the bottleneck is the goal of the metrology community, as they say, if you cannot test something, you cannot manufacture it.

Using the properties of speckle to get better measurements

The metrology community has made significant advances by making improvements to existing techniques to test X-ray mirrors. However, a team from Diamond set about creating a brand-new instrument which can potentially improve the toolbox for metrologists and manufacturers around the world.

Read more on the Diamond website

Image: Dr Hongchang Wang (Left) is supervising his PhD student Simone Moriconi (Right) for testing SAM system

Disorder brings out quantum physical talents

Quantum effects are most noticeable at extremely low temperatures, which limits their usefulness for technical applications. Thin films of MnSb2Te4, however, show new talents due to a small excess of manganese. Apparently, the resulting disorder provides spectacular properties: The material proves to be a topological insulator and is ferromagnetic up to comparatively high temperatures of 50 Kelvin, measurements at BESSY II show.  This makes this class of material suitable for quantum bits, but also for spintronics in general or applications in high-precision metrology.

Quantum effects such as the anomalous quantum Hall effect enable sensors of highest sensitivity, are the basis for spintronic components in future information technologies and also for qubits in quantum computers of the future. However, as a rule, the quantum effects relevant for this only show up clearly enough to make use of them at very low temperatures near absolute zero and in special material systems.

Read more on the HZB website

Image: The Dirac cone is typical for topological insulators and is practically unchanged on all 6 images (ARPES measurements at BESSY II). The blue arrow additionally shows the valence electrons in the volume. The synchrotron light probes both and can thus distinguish the Dirac cone at the surface (electrically conducting) from the three-dimensional volume (insulating).

Credit: © HZB