Meet the Jury Aleš Hrabec on Patterning two-dimensional gradients in structural and magnetic properties for spintronics and magnonics applications

Arenberg Doctoral School is proud to invite you to Meet The Jury!

When internationally renowned experts visit KU Leuven as a member of a PhD Examination Committee, we like to seize this opportunity to give this expert a forum to a large audience. All members of Science, Engineering & Technology are most welcome to the Meet The Jury Lectures.

Dr. Aleš Hrabec (UTH Zurich, Switzerland) will give a lecture on “Patterning two-dimensional gradients in structural and magnetic properties for spintronics and magnonics applications”.

Novel spin-based logic architectures are being developed to provide high-performance nonvolatile data retention and processing. Two prominent directions include the development of spin-based in-memory computing and efficient, all-electric control of magnetic order. We have recently showed that spatial patterning of uniaxial anisotropy via selective oxidation can result in strong lateral coupling based on the Dzyaloshinskii–Moriya interaction [1]. The coupling can be incorporated into electrically-controlled devices comprising reconfigurable NAND and NOR logic gates [2]. Despite the limited number of material systems where such in-memory computing can be realized, the capability of patterning magnetic anisotropy opened unprecedented avenues. This discovery highlighted the need to develop new methods for spatial patterning, which could lead to new, disruptive technologies in magnetism and beyond. To enhance the pool of structural and magnetic properties that can be patterned, we have developed direct-write laser annealing, which is based on local annealing [3]. Here, the underlying magnetic properties are linked to heat-activated processes such as crystallization, interdiffusion or oxidation. We demonstrate the capability of this technique by realization of a spin wave band pass filter and new architectures for passively resetting the position of a magnetic domain wall [3,4]. We also demonstrate that conventional and unconventional spin-orbit torques can be patterned based on the underlying designed structural gradients in tungsten thin films [5] as well as patterning magnetic properties in thin TmIG films. The laser annealing-based method opens new opportunities to pattern material and magnetic landscapes with high-precision capability, leading to unprecedented applications in spintronics and magnonics, and thin-film based magnetism in general.
References 1. Z. Luo et al., Science, 363, 1435 (2019). 2. Z. Luo et al., Nature 579, 214-218 (2020). 3. L. Riddiford, J. A. Brock et al., Nat. Commun. 16, 10979 (2025). 4. J. Brock et al., Nano Lett., 26, 16, 5426–5433 (2026). 5. L. Riddiford, et al., arXiv:2601.01429 (2026).

Additionally, Dr. Liza Herrera-Diez (C2N, CNRS, Université Paris-Saclay, France) will give a lecture on “Magneto-ionic synaptic devices”.

The ability to manipulate magnetic properties through ionic motion in ferromagnetic/oxide structures in a non-volatile way, rather than through volatile, purely electronic means, presents exciting opportunities for the development of functionalities like reconfigurable multistate memories and the implementation of cumulative gate effects in spintronics devices. Magneto-ionics takes inspiration from memristor technologies and offers one of the most advanced approaches today for controlling magnetic properties using ionics. Integrating ionic and spintronic technologies offers new degrees of freedom to design neuromorphic hardware with novel magnetic functionalities, alongside the established ionic analogue behavior. I will present different strategies to develop multistate magneto-ionic memory devices using CoFe alloys. A variety of material combinations and device designs allows to explore the control of nucleation/propagation of a spin-reorientation transition under gate voltage and the exploration of an extended gate-induced oxidation-reduction spectrum to generate multiple stable, electrically detectable magneto-ionic states. I will also demonstrate that magneto-ionic nanodevices can not only function as basic synaptic elements, using their capacity to encode multiple analogue states, but also enable new bioinspired functionalities. We show that in magneto-ionic synaptic elements, synaptic depression can be tuned using a magnetic field, allowing to dynamically control the linearity of the synaptic weight update. This functionality is reminiscent of neuromodulation, observed in biological systems, and neural network simulations reveal that a magnetically induced enhancement in weight-update linearity improves learning accuracy across a wide range of learning rates. These findings highlight the versatility and promise of magneto-ionic devices for developing multifunctional synaptic elements for neuromorphic hardware.
References [1] G. Bernard, K. Cottart, M-A. Syskaki, V. Por´ee, A. Resta, A. Nicolaou, A. Durnez, S. Ono, A. Mora Hernandez, J. Langer, D. Querlioz and L. Herrera Diez, ‘Dynamic Control of Weight-Update Linearity in Magneto-Ionic Synapses’ Nano Letters 25, 4, 1443–1450 (2025). [2] G. Bernard, X. Lafosse, C. Tataru, M.-A. Syskaki, A. Durnez, F. Mahut, D. Ravelosona, J. Langer and L. Herrera Diez, ‘Magneto-ionic Control of a Propagating Spin Reorientation Transition’ Nano Letters 25, 32, 12241–12247 (2025). [3] I. Benguettat-El Mokhtari, R. Pachat, V. Porée, A. Lamperti, Y. Roussigné, M.-A. Syskaki, J. Wrona, G. Bernard, A. Cataldo, A. Resta, A. Nicolaou, S. Ono, J. Langer, D. Ravelosona, M. Belmeguenai, A. Solignac, L. Herrera Diez, ‘Exploring the full magneto-ionic oxidation spectrum in Pt/CoFeB/HfO2’, Appl. Phys. Lett. 126, 232402 (2025). [4] T. da Camara Santa Clara Gomes, T. Bhatnagar-Schöffmann, S. Krishnia, Y. Sassi, D. Sanz-Hernandez, N. Reyren, M-B. Martin, F. Brunnett, S. Collin, F. Godel, S. Ono, D. Querlioz, D. Ravelosona, V. Cros, J. Grollier, P. Seneor, L. Herrera Diez, ‘Control of the magnetic anisotropy in multi-repeat Pt/Co/Al heterostructures using magneto-ionic gating’ Phys. Rev. Applied, 21, 024010 (2024). [5] T. Bhatnagar-Schöffmann, P. Schöffmann, A. Resta, A. Lamperti, G. Bernard, A. Kovacs, L. Largeau, A. Durnez, A. Harouri, X. Laffosse, D. Ourdani, M.-A. Syskaki, Y. Roussign´e, S. Ono, R. E. Dunin-Borkowski, J. Langer, D. Ravelosona, M. Belmeguenai, A. Solignac and L. Herrera Diez, ‘Non-oxidative mechanism in oxygen-based magneto-ionics’ Adv. Mater. Interfaces 2300955, (2024).
Agenda:
-15:00 – 15:50: Dr. Aleš Hrabec (ETH Zürich, PSI, Switzerland): “Patterning two-dimensional gradients in structural and magnetic properties for spintronics and magnonics applications”
-15:50 – 16:00: Coffee break
-16:00 – 16:50: Dr. Liza Herrera-Diez (C2N, CNRS, Université Paris-Saclay, France): “Magneto-ionic synaptic devices”

Following the lecture, there will be opportunity for young researchers to interact with them.

• Venue: Imec cafetaria -1B (3001 Leuven – Onsite participants can meet at the entrance of Imec 1 at 14:45 and Bob Vermeulen will guide them to the room) or online via Teams (Registration for participants with Imec account – Registration for external participants)
• Date: 20 October 2026 – 15:00-16:50
• Dr. Aleš Hrabec and Dr. Herrera-Diez are visiting KU Leuven on the occasion of the PhD defence of Bob Vermeulen