Research: New Methods for Magnetic Microscopy

2021-07-12

In an international collaboration with physicists from Germany and Russia, has Uppsala researcher Peter Oppeneer developed new and simpler methods for magnetic microscopy, which is an important characterization technique, for example, for the development of magnetic memories.

With the help of magnetic microscopy it is possible to identify so called magnetic domains, which are micro- or even nanometer sized areas in materials, where all atoms have a magnetisation pointing in the same direction.

In the common form of magnetic microscopy, researchers exploit the magneto-optical Kerr effect, which means that initially non-polarised light, that has been polarized by directing it through a polarizer, and then used to irradiate a magnetic material, is reflected and thereby changes polarisation direction to a certain amount.

The change of the polarisation direction is in direct proportion with the material’s microscopic magnetisation and can be measured with an optical analyser. Through the detection of the polarisation change, the microscopic magnetic domains become visible.

Through detection of polarisation changes, microscopic magnetic domains become visible. The image shows microscopic magnetic domains depicted in a conventional magneto-optical microscope. The arrow shows in which direction the magnetisation points in the various domains. Image: R. Schäfer

Within magnetic microscopy one has up to now needed both a polariser, to polarise the light in a single direction, and an analyser, to detect the direction of polarisation. The new research study shows though that there are new, previously unknown, methods to detect the magnetisation.

In the newly published research study, the researchers have now been able to show that there are several novel methods for magnetic microscopy that not demand an analyser, and, in some cases, not even a polariser. For example, it is possible to detect a change in the intensity due to the magnetization without an analyser.

– This means that in the future magnetic microscopy can become significantly simpler and more widely available within research, says Peter Oppeneer, Professor at the Department of Physics and Astronomy.

The study was published in Applied Physics Reviews which is one of the most reputable journals in applied physics. Rudolf Schäfer’s research group in Dresden, Germany, has performed the experimental microscopic observations based on the theory of the magneto-optical effects, developed by Peter Oppeneer at Uppsala University.

Contact

Peter Oppeneer, tel. 0709-604016, peter.oppeneer@physics.uu.se

Article Reference

R. Schäfer, P.M. Oppeneer et al., Analyzer-free, intensity-based, wide-field magneto-optical microscopy, Applied Physics Reviews 8, 031402 (2021), Publication Date: July 13, 2021, DOI: https://doi.org/10.1063/5.0051599

Camilla Thulin

Translation: Johan Wall

Last modified: 2021-08-31