Focused ion beam opens the door to highly sensitive probes – New EU project approved

A commercially available atomic force microscope (AFM) cantilever milled by FIB. (Image: Department of Physics, University of Basel)

Argovia Professor Martino Poggio of the University of Basel’s Department of Physics is to lead a recently approved project under the European Horizon 2020 program. Working with researchers from IBM Research – Zurich, the University of Tübingen and the Consejo Superior de Investigaciones Cientificas (CSIC) in Zaragoza, Poggio’s team aims to develop a new production method for exceptionally sensitive and precise probes for scanning probe microscopy that can also be used to examine superconducting materials. In the project, which is funded by FET Open – a scheme supporting European cooperations developing radically innovative technologies – the researchers will use focused ion beam (FIB) technology to fashion the sensors.

Sensor directly on the cantilever tip
“We hope to usher in a new era for the already highly successful field of scanning probe microscopy,” Poggio announced in response to the news of the project’s approval. “By using focused ion beam technology, we can manufacture tiny, highly sensitive sensors directly on the cantilever tip, capable of imaging even superconducting samples at the nanoscale with previously unprecedented levels of contrast.”

The researchers chose versatile FIB technology for the unparalleled flexibility it offers in comparison to other techniques. Besides removing material, FIB can also be used to deposit or structurally alter substances – with nanometer resolution, on both even and uneven surfaces. The probes, which will contain nanometer-sized Josephson junctions (JJs) and superconducting quantum interference devices (SQUIDs), will serve to image magnetic fields and susceptibility, besides enabling measurement of electrical currents and their losses.

The new cantilevers will be manufactured and fitted with the appropriate probe at the tip depending on the intended application. As well as allowing distance control, they will make it possible to image samples with outstanding spatial resolution and unprecedented contrast. “The new probes will broaden the potential applications of scanning probe microscopy, allowing us to tackle poorly understood phenomena in physics, chemistry and materials science that can’t be studied using current technology,” said Poggio.

Initially, applications will focus on studying magnetic fields in two-dimensional and van der Waals materials. The researchers are especially interested in mapping the transport of charges, and imaging edge states and correlated electronic states. The examinations can be performed at comparatively high temperatures of up to 80 Kelvin (-193°C), with a spatial resolution of up to 10 nanometers.

SNI involvement
The project was originally due to begin in October 2020, but could be postponed due to the coronavirus pandemic. In any case, the project teams have secured funding of almost three million euros in total over four years.

The SNI’s Nano Imaging Lab has already played a crucial role in the project: The preparatory groundwork confirming the idea’s general feasibility and paving the way for the project proposal was achieved by Dr. Marcus Wyss from Poggio’s team using the NI Lab’s FIB.

“My heartfelt congratulations to the project team!

I am glad that a few years ago I could facilitate the purchase of the FIB, and I am very excited about the results that this promising project will bring for our research.”

Professor Christian Schönenberger, SNI Director


More information about the Poggio Lab