Interview: Dr. David Albertini
As a CNRS research engineer, how do you help the advancement of science in academia?
My work (and more generally the work of research engineers) covers several aspects. First of all, I provide experimental support to other researchers thanks to my technical expertise but also to my scientific knowledge. In the French research system, those who best know laboratory instrumentation are often engineers or technicians. I also develop new techniques or procedures to get the most out of my microscopes, which I maintain and keep up to date. I always try to obtain the best possible resolution on more and more complex samples – in particular with modes such as piezoresponse force microscopy (PFM), for example.
So one could say that my role is to pass on my knowledge, train students and researchers, as well as to extend the possibilities of microscopes and bring new modes to the laboratory. The bimodal mode for nanomechanics on soft materials is a good example of the latter aspect; the HF2LI Lock-in Amplifier will be highly involved in this work!
What exciting projects have you recently worked on?
Working in ultra-high vacuum (UHV) conditions on the Omicron VT-AFM is a real pleasure. This summer, I studied ZnO layers in Kelvin probe force microscopy (KPFM) at different temperatures with Alexander Singaevsky: we had a great time, because we discovered new things with every new image. With Etienne Puyoo, we conducted a new study with scanning Joule expansion microscopy, which is an indirect method for thermal imaging at the nanoscale. We looked at the physical expansion of the material under stress via atomic force microscopy (AFM). This was partly achieved with the HF2LI, but the mode remains to be developed further.
I also like to push PFM, the laboratory's flagship mode, to its extreme limits. Attaining high resolution on KNNO in lateral PFM or doing PFM through electrodes is very motivating as it opens perspectives for more difficult materials (such as the HZO I am currently working on with Nicolas Baboux).
You have been an HF2LI user for more than 6 years now, and you have used it on several setups: what are the advantages of this type of instrument for an engineer like you?
When the first HF2LI arrived in the laboratory, Brice Gautier and I knew exactly what we wanted to do: frequency tracking for PFM. The HF2LI allowed us to achieve this, and we made good experimental and scientific progress in our understanding of ferroelectric materials. Very quickly, I saw the opportunity to share this knowledge with the community, as I convinced myself that the HF2LI would become more popular in other laboratories too. With Michel Ramonda, who already used his HF2LI for contact resonance AFM, we decided to propose PFM and nanomechanics workshops with funding from the CNRS RéMiSoL network. This project was a success: there is now a solid community of specialists. For example, Denis Mariolle developed KPFM in a single-pass scheme and we organized workshops on this subject in Grenoble.
It takes time to understand the HF2LI’s capability in depth, but the software interface improves with each version and is of great help. I think I master a tiny part of the HF2LI electronics. What is clear is that for modes such as dual-frequency resonance tracking PFM, the HF2LI is precise, is characterized by very low noise and gives maximum performance.
The COVID-19 pandemic has greatly affected work in laboratories around the world. Have you found ways to control experiments remotely or work on projects that do not require you to be in front of an AFM?
In March, at the time of the first confinement period, my biggest regret was to not have brought an HF2LI at home to try to interface it with Python. I have since made up for it thanks to Adrianos Sidiras Galante, who programmed Zi² under my supervision: this tool allows us to capture the signals from the HF2LI (synchronized to the Bruker Nanoscope V electronics) and plot them in AFM images. The code is available on GitHub. This experience made me realize that programming is a full-time job!
Apart from programming AFMs, what are your hobbies?
Since 1994 and my first encounters with the internet, I have been programming websites (for the RéMiSoL network and the Forum event, for example); during the first confinement I worked on my personal blog, which focuses on my scientific research. I also like video games, which I play with the participation of my cat Miù. I love listening to music, and have recently started as a hobbyist in the HiFi area, which turns out to be a huge and highly scientific world as well!