Graduating student Pascal Haazen has publication in top journal Nature Materials

He graduated last September with a 10, which had never before been achieved in the Physics of Nanostructures group in the Applied Physics department. And now Pascal Haazen’s graduation project, about the propulsion of magnetic bits in nanowires, has been published in the leading journal Nature Materials. The article went online on Sunday 3 February. The findings are very important for the development of the ‘racetrack memory’.

Special praise comes from Henk Swagten, who supervised Haazen’s graduation. “Pascal came up with the ideas, carried out all the experiments, did the interpretation and modeling, and then wrote the paper for Nature Materials himself, including the discussions with the referees. That’s quite exceptional, and I’ve never seen it before at graduation level.”

Mont Blanc
There are a few more special items on Haazen’s CV. He did a research internship at the renowned MIT in the USA, with a grade of 9.5. That led to a publication in Applied Physics Letters, also a remarkable achievement. As well as that he’s climbed Mont Blanc, and was chairman of the university’s Dynamos power sports club.

Propelling nanobits
Haazen’s graduation project is about magnetic bits in nanowires. He thought up a new way to make these bits move. Up to now this was done by applying a current to the magnetic layer with the nanobits. However Haazen has done this indirectly: applying a current to the adjoining layer causes the ‘Spin Hall Effect’, which propels the nanobits in the magnetic layer. The results are of great importance for the development of the ‘racetrack memory’, a promising new data-storage technology which is needed because conventional semiconductor memory will soon reach the limits of its development.

Back and forward
This limitation arises because each bit in a normal semiconductor memory is connected to a ¬– relatively large and costly – transistor. In magnetic storage, such as in a hard disk, this is not the case. But a hard disk is much too slow to replace semiconductor memories. This is the reason for the development of the racetrack memory, in which much more data can be stored than in today’s memory chips. In this kind of memory the magnetic bits – ultra-small regions with varying magnetizations – flow backwards and forwards through a nanowire and past the read and write head. All the components are static and only the data moves, which means the system is also very energy-efficient.

“This research not only contributes to a better understanding of the Spin Hall Effect, but will also lead to new nanoelectronics in which magnetic information can be stored and read-out in a unique and alternative way on a nanometer scale”, said prof. Swagten.

The article ‘Domain wall depinning governed by the spin Hall effect’ was published on 3 February in Nature Materials, DOI 10.1038/NMAT3553. The authors are P. P. J. Haazen, E. Murè, J.H. Franken, R. Lavrijsen, H.J.M. Swagten and B. Koopmans, all at Eindhoven University of Technology (TU/e). Nature Materials has an impact factor of 32.