We04 Seminar "When noise becomes data: thermal fluctuations in nanomagnetic systems" by dr. Jonathan Leliaert

20-02-2020 from 14:00 to 15:00
S9, multimediaroom
dr. Jonathan Leliaert
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On the nanoscale, temperature is a strong force that gives rise to fluctuations that are typically regarded as unwanted noise. In contrast, we are harnessing this noise and extract useful data from it to characterize magnetic nanoparticles.

In recent years, magnetic nanoparticles have attracted a lot of interest due to their appealing properties for biomedical applications. This can be attributed to the unique combination of their small sizes, giving them virtually full body access, and a large magnetic moment, enabling noninvasive steering and detection.

However, for these applications to work safely and reliably, the nanoparticle properties should be well known and their dynamic behavior should be fully understood.
Typically, magnetic nanoparticles are investigated by measuring their response to externally applied magnetic fields. However, such external excitations affect the aggregation state of the particles by e.g. inducing chain formation, and thus influence the measurement results.

We recently demonstrated the feasibility of a new approach, in which the noise signal resulting from the thermal switching of the nanoparticles in the absence of any external excitation is measured. With the help of SQUIDs in a magnetically shielded environment, a noise spectrum originating from the nanoparticles has been observed, and the shape of the spectrum was interpreted to estimate the properties of the nanoparticles.