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Aico Troeman (promotion date: 13 December 2007)

Nanosquid magnetometers and high resolution scanning squid microscopy

Promotion date: 13 December 2007

Besides being an extremely tiny sea animal (laughs),

a nanoSQUIDs is an acronym for a nano Super-

conducting Quantum Interference Device.

It is a miniaturized version of the most sensitive

magnetic field sensor in existence.

A SQUID is a structure comprised of a ring of

superconductive material incorporating two so

called Josephson junctions which, when cooled to the

right temperature, can measure fields down to fT´s

(femto tesla).

Why would you want to do that?

Curiosity, for one. Besides, nanotechnology is hot. And there are reasons enough to study the magnetic properties of materials. You could think of biotechnology and the magnetic properties of living tissue or magnetic field patterns above modern nano-sized electronic circuitry. But fundamental knowledge always comes first.

A scanning squid microscope is a piece of equipment with which you can scan a squid over the surface of a sample while measuring minute variations in magnetic field. The smaller the structures on such a surface, the smaller the squid should be to be able to measure the resulting magnetic field patterns.

Squids have been around ever since the 60’s of the last century. I miniaturized the squid and described the changes in the physical mechanisms determining the performance of such small sensors. This accounts for the fundamental parts of the thesis. Furthermore, I developed a high resolution scanning device.

Did it work?

It did, yes.

What did you like best about your research?

I enjoyed the conferences that are held all over the world in the field of Superconductivity.

Canada, US, all over Europe. If you enjoy travelling, doing a PhD is a good option. You meet different people and learn about their culture.

And of course I enjoyed the challenge of the research. You have to do it yourself from A to Z: the analysis of the problem, thinking up a possible solution, execution of the solution and drawing a general conclusion if possible.

That in itself is also the problem of a promotion: it is somewhat of a lonely job. There is hardly anybody to share your ideas with.

How did you solve that problem?

The conferences. There are two or three groups in the world working in the same field and eventually you meet the persons involved.

Any setbacks?

No, not really. Although I must say it is a bit harder to keep up the motivation in the period between the finalization of the thesis and the actual defence ceremony.

What are your plans?

To live happy ever after…. (laughs).

No seriously: I will start work with OCE Technologies as an Application Researcher. In close collaboration with clients and the R&D department we will tackle latent and future problems and formulate innovation lines to improve the competitiveness of the company. By the looks of it I will leave the purely scientific world, but you never know. But now I think it is time to do something entirely different and to enter a new world.

For the summary of the thesis, click here