My current project delves into unexplored territories of spintronics; control of magnetization-dynamics by using synthetic-multiferroic-heterostructures.
My objective is to obtain full-control over the magnetization-dynamics of a (nano-)magnet without using magnetic fields.
I foresee that this will result in a novel way of power-efficient and fast-coherent-control of magnetization. This has a huge potential for creating commercial devices (memory, data-storage, logic) and will create new paradigms in the fundamentals of the underlying physics by new ways of probing competing interactions in a cleverly chosen, simple materials/device system.
January 2018 - I am very pleased to announce that I have obtained Tenure at the TU/e. I am looking forward to pursuing the lines of research I have set out with even more confidence! A big thanks to the committee who put me through a thorough review process and for the trust they invested in me!
15 December 2017 - A short update in these turbulent times. The department of Applied Physics at the TU/e (my department) needs to reorganise due to the changing funding landscape in the Netherlands which we have not been able to follow, a sad but necessary measure. It seems that the policy makers only want applied research and shy away from the more fundamental approach. At the same time the end of my tenure track period is approaching and a decision will be taken on the 'in or out' before the end of the year. I am confident that I fully qualify for the positions but due to the aforementioned factors all is unsure if the outcome would be 'in', it will stay that way. But let's not run ahead of the process and await the decisions first. Keep tuned for the outcome, the champagne has been in the fridge for too long now.
On the research side all is progressing rather well, 5 new manuscripts have been accepted since september 2017 (!) (see publications section). Moreover, the realization of a start-up around the nanoplatelet projects is becoming more of a reality. Together with University Maastricht we are submitting a proposal to the Dutch Cancer Society (KWF) to investigate the effectiveness of the particles for cancer treatment, and the first images of the particles in cancer tissue (organoids) are expected this week, exciting! Keep tuned.
25 September 2017 Great news; the first paper on which I feature as last author has just appeared in Applied Physics Letters (link) featuring Juriaan Lucassen's efforts on using SEMPA to show that this technique can be used to image chiral textured domain walls in multi-layered films. This is a joint output with the university of Hamburg who are experts in the field of SEMPA. This has given us a jump start to using our own in-situ SEMPA on the NanoAccess system. Furthermore, a recent paper featuring new material combinations for solar fuels has just appeared; another fruitful collaboration with the DIFFER institute. Meanwhile, I have been writing hard on grant proposals and scouting the funding landscape for further funding opportunities for the magnetic nanoparticles, too bad this eats so much of my time that I would rather spend in the lab or training students. Another challenge is facing me which is preparing for the lectures of the massive first year course Applied Physics at the TU/e, a new challenge for me regarding amount of students and diverse topics, but looking forward to it!
A different massive milestone for me personally is the departmental approaching decision on getting Tenure ...or not... at the end of this year. I hope that all my effort and generated output are enough to grant me this position, I love the work I do (a little less grant writing would make it even better). I have the feeling that all depends on the funding landscape, which is something that one has so little control over. I guess it is just a matter of keeping my fingers crossed and work hard, so back to it...! Ow yes, before I forget, if you would like to know a bit more about nanomagnetism I invite you to the Science Festival on the 8th of October at the TU/e where I will give a short talk on the wondrous world of nanomagnetism.
June 2017 After winning the NWQ last december (see news section) and enjoying the great trip to La Palma to visit the observatory I have been busy in the lab. 4 new papers (see publications) have come out where my collaborative and facilitating role around the NanoAccess system has come to fruit; the layers produced in our system are exposed to intense He-beams and thereby nanostructured. Differ is investigating if these might be interesting for solar fuel applications. Furthermore, two papers are published describing peculiar behavior of domain walls and magnetization in epitaxial RKKY coupled bilayer systems. Finally, the work on specially engineered zig-zag wires allowing us to efficiently measure the chiral domain wall resistance has been published in Applied Physics Letter. As an outlook I can say that our latest work on SEMPA is nearly ready to be sent off for review and some interesting collaborations have recently been started in my endeavours in Skyrmionics and our recently started pilot-project on specially engineered Nanoparticles. Hope to post some movies soon showing their dynamic behavior!
January 2017 Great News, we won the National Science Quiz which was broadcasted on Christmas day on national television. You may watch it here (sorry only in Dutch). I was teamed up with Frederique Spigt, not only a very talented musician but also a lot of fun to be around, especially when on a quiz ;-). I am very pleased to add this honour to my CV and am looking forward to the prize: a trip to La Palma to visit the famous Observatorium Roque de los Muchachos co-funded by NWO where we will enjoy a tour by one of the scientists.
Photo by Robert Lagendijk.
14/10/2016 Some interesting times have started. I have just submitted two big research proposals, let's keep our fingers crossed that the referees and committees are open to the exciting new research directions I have sketched. I am really excited to start on the projects and have some pilot experiments running but to generate full momentum these grants are really needed. Furthermore, I have been asked to compete in the Nationale Wetenschaps Quiz! A TV program of the dutch public broadcasting agency VPRO. So I will be on TV this Christmas, what a blast, really looking forward to the recording but also a bit anxious as to how I will appear on TV. Finally, the next session of the NanoMagnetism course is about to start, two new shiny setups Mini-MR-MOKE have been installed to give the students full hands-on experience on typical experiments and magnetic phenomena in thin ferromagnetic films.
21/03/2016 Check out the latest article on probing individual buried nanolayers in a multilayer stack in the publications section. This article describes a method for full magnetic characterisation of buried nanolayers as used in soliton ratchets. Furthermore, two master students have recently graduated with excellent marks. Both MSc. Dorris Slapak and MSc. Guido Hendriks did a terriffic job on the synthetic-multiferroics, we are currently writing up the first article on this work.
22/12/2015 The end of the year is nearly there, also the end of my VENI scholarship, which means to reflect back on the research and change of the last three years. I have managed to move into a Tenure track, so the VENI has brought me very far! This has also brought me many managerial and teaching commitments. This is both for the good and the bad. A small bad due to the limited time I can now spend on research but a big good due to the new challenges that have come my way. The teaching of a NanoMagnetism course has given me many new insights and angles to look at my own research and at motivating and teaching students. Moreover, the setting up of an experimental part in the course has worked out great and the students enjoy to 'bringing into practise' the abstract concepts they learnt during the lectures. Finally, I have been elected into the department council which is a great honour and I will give it my full effort.
15/10/2015 I am pleased to announce that I enrolled into a Tenure-Track position at the TU/e. My hard work and commitment to research and teaching have made this possible. I am fully dedicated to push through and expand my current research line and position. This on coincidence happened very close to the birth of our first child, Loore, what a small wonder! On the research side everything is slowly but steadily progressing, the time investments in optimization and technology are begin to show and some intriguing results of the electric field effect on the interlayer exchange coupling and on the synthetic-multiferroics are starting to show up, stay tuned....
15/06/2015 The manuscript that has been long in the making has been accepted for publication in Nature Communications and is entitled: "Thickness dependence of the interfacial Dzyaloshinskii–Moriya interaction in inversion symmetry broken systems". This is a collaborative effort with the group of Chun-Yeol You Inha University in South-Korea where they found that Brillouin light scattering is an excellent technique to probe the Dzyaloshinskii–Moriya interaction in the samples originating from our labs, you can find it here.
12/03/2015 Good news, our latest paper where we explored the asymmetric expansion of ferromagnetic bubbles in differently prepared Pt/Co/Pt has been accepted for publication in Phys. Rev. B. This was a collaborative work together with the theory department (Rembert Duine and Dion Hartmann) of the Utrecht university. It details the effect of growth parameters and how this translates into different velocity profiles. The results are far from understood and further theoretical development is called for.
08/08/2014 I am very very pleased to have been invited to talk at the 59th annual Magnetism and Magnetic Materials (MMM) conference 2014 in Honolulu, Hawaii, this November. Here I will present our latest data on Bubble expansion with DMI interactions and relate this to our depinning experiments, really looking forward to it! I have added two articles to the publications section, both from the hands of Jihyun Lee who is very good in getting data out of the Soliton samples we produced while I was in Cambridge, great work! Furthermore, I have hit a h-index of 10 on Web of Science, a small victory for myself.
In the lab we are installing a large UHV cluster tool including, a massive 12 target sputter chamber with integrated 7 pocket E-beam evaporator. A surface analysis chamber with LEED, UPS, XPS, AES. A preparation chamber with ion-gun, annealing with magnetic field, and oxidation. In the future this system will be expanded with a UHV cryogenic 4-probe scanning probe chamber. And finally a SEM(PA)/FIB chamber will be added. The unique part of the systems is that it will all be interconnected via a UHV transport system allowing freshly prepared samples to be transported to different chambers in a UHV environment. We expect this will provide us with many new insights of, for instance, the relation between the Dzyaloshinskii-Moriya interaction and structural properties such as inversion asymmetry in ultrathin films. See the gallery for some fresh pictures.
19/02/2014 Two new articles have been added to the publications section. The first describes the behavior of multiple solitons in a single multilayered stack allowing cool logic operations, fully in the magnetic state! The second describes the pinning of domain walls by deposition magnetic nanopillars on top of domain wall conduits by focused electron beam induced depostion.
Teaching and getting students enthousiastic in my research topic makes my day. They are not only an indispensible way of carrying the work forward, their insights, questions and different personalities keep me sharp and human(e).
In this project Dorris Slapak explored the RF sputter deposition of BaTiO3 concentrating on stoichiometry, crystallography and ferroelectric properties. She graduated in February 2016 and is persuing a career in industry.
In this project Mark Lalieu explored the effect of a gate voltage on the RKKY coupling in ultrathin magnetic layers. The first effects have been observed and will be published soon. He graduated officially in November 2014 and has decided to continue as a PhD student in our group working on ultrafast magnetization dynamics.
Juriaan set out to develop a new way of measuring the spin Hall effect using a technique based on superconductors. He is building a model framework and rebuilding the measurement equipment used for the the sensitive measurements. He graduated in November 2015 and is currently persuing a PhD in our group working on thin film skyrmionics in collaboration with the theory group of Rembert Duine at the Utrecht University.
Guido sets out to build a low power magnetization switching device combining piezo actuators and thin magnetic films with high magnetostriction. He focuses on optimizing the coupling and novel ways to break the switching symmetry to realize full 180 degree magnetization reversal.
Pim sets out to measure the Dzyaloshinkii-Moriya interaction (DMI) in a variety of ultrathin magnetic multilayers. By exploring trends a better understanding of the DMI is expected.
In this project Rens Raijmakers sets out to explored the effect of a gate voltage on the RKKY coupling in ultrathin magnetic layers. He has taken over the project from Mark Lalieu and is concentrating on efficient data gathering and optimizing the devices.