O akci
Enric Menéndez Dalmau
Prof. Menéndez's research benefits from national and international formation in Spain, Germany (1 year) and Belgium (6 years). As a result, he has built a strong, broad and applied-oriented background in the cross-fertilization of ion irradiation and nanomagnetism for spintronics. His research track record is based on 51 published articles in peer-review journals (48 appear in Web of Science), a filed patent on a magnetic patterning approach based on local mechanical deformations, 22 invited talks and 19 talks presented in major conferences in the fields of ion beam modification of materials and magnetism. He is strongly committed to teaching, to the formation of young scientists and to outreach. He has already supervised 3 PhD Theses and is currently supervising 2 more, as well as several Master Theses. Singular of his track is the expertise he has gained at large scale experimental facilities to explore the properties of materials at the nanoscale with intense beams of neutrons and photons. Specifically, Prof. Menéndez has participated in 25 research projects (13 as principal investigator) at centers such as ESRF (synchrotron, France), BESSY II (synchrotron, Germany), ALBA (synchrotron, Spain), ILL (neutron reactor, France), BERII (neutron reactor, Germany), MLZ (neutron reactor, Germany), NIST Center for Neutron Research (neutron reactor, USA) or ELBE (radiation source, Germany).
TOPIC: Controlling magneto-ionics in Co3O4 by defect engineering through ion implantation
Magneto-ionics relies on the voltage-driven transport of ions to modify magnetic properties. As a diffusion-controlled mechanism, defects play a central role in determining ion motion and, hence, magneto-ionic response. We will talk about the potential of ion implantation to engineer depth-resolved defect type and density with the aim to control the magneto-ionic behavior of Co3O4 thin films. We demonstrate that through a single implantation process of light ions (He+) at 5 keV, the magneto-ionic response of a nanostructured 50 nm thick Co3O4 film, in terms of rate and amount of induced magnetization, at short-, mid-, and long-term voltage actuation, can be controlled by varying the generated collisional damage through the ion fluence. These results constitute a proof-of-principle that paves the way to further use ion implantation (tuning the ion nature, energy, fluence, target temperature, or using multiple implantations) to enhance performance in magneto-ionic systems, with implications in ionic-based devices [1].
[1] Z. Ma, S. Martins, Z. Tan, S. Chen, E. Monteblanco, M. O. Liedke, M. Butterling, A. G. Attallah, E. Hirschmann, A. Wagner, A. Quintana, E. Pellicer, D. Ravelosona, J. Sort and E. Menéndez, Controlling Magneto-Ionics by Defect Engineering Through Light Ion Implantation, Advanced Functional Materials (2024) 2312827 (https://doi.org/10.1002/adfm.202312827)
Jordi Sort Viñas
Jordi Sort leads the ‘Group of Smart Nanoengineered Materials, Nanomechanics and Nanomagnetism’ (with around 20 researchers) as an ICREA Research Professor at UAB. After finishing his PhD in 2002 in the field of “magnetic interfacial effects” (Extraordinary Award), Prof. Sort performed two postdoctoral stays, at SPINTEC (Grenoble) and at Argonne National Laboratory. His research is focused on a wide variety of materials (thin films, lithographed structures, porous materials and nanocomposites) with emphasis on their magnetic, magnetoelectric and mechanical performance. He received awards from the Catalan and Spanish Physical Societies as well as the Federation of European Materials Societies. At present, Prof. Sort has supervised 16 PhD Theses, has published more than 320 articles (with around 10.000 citations in Web of Science, H-index = 50), has issued 6 patents, and has managed more than 30 national/international research projects, being Coordinator of two European Training Networks (ITN) and a Consolidator Grant and a Proof-of-Concept Grant from the European Research Council.
TOPIC: Nitrogen magneto-ionics: fundamentals and prospective applications
In a similar way as bringing spin to electronics has revolutionized information technologies through the field of spintronics, merging magnetism with iontronics (magneto-ionics) has a lot of potential for the development of analogic magnetic memories and their application in emerging research areas such as neuromorphic computing. In this talk I will review the recent progress in voltage-driven ion motion in transition-metal nitrides, a particular class of materials where ferromagnetic, paramagnetic and antiferromagnetic phases can coexist depending on the alloy composition and the nitrogen concentration. We will show that voltage-driven transport of nitrogen ions can be triggered at room temperature in CoN, FeN, CoFeN and CoMnN films via liquid and solid electrolyte gating [1,2]. Nitrogen magneto-ionics can induce reversible ON-OFF transitions of ferromagnetic states at faster rates and lower threshold voltages than oxygen magneto-ionics. In addition, and in contrast to oxygen magneto-ionics, nitrogen transport tends to occur uniformly through a plane-wave-like migration front, an effect particularly interesting for the implementation of multi-stack memory devices. We will show strategies to further increase the magneto-ionic switching rates in this class of materials, as well as cyclability. New physical phenomena arising in patterned nanoscale magneto-ionic systems will also be described. Nitrogen magneto-ionics can be used to emulate some important synaptic functionalities. By cumulative effects of pulsed voltage actuation (at frequencies in the 1 – 100 Hz range), learning, memory retention, forgetting and learning by maturity (post-stimulated learning) can be mimicked [3]. This latter effect can serve as a logical function for the device to decide between self-learning or forgetting emulation, at will, without any electric voltage input. Finally, I will also show the possibility to induce magneto-ionics without any wire connection to the sample, through a phenomenon called bipolar electrochemistry [4]. This effect could bring magneto-ionics into novel research domains, such as wireless biomedical applications.
Acknowledgements
This work has been supported by the European Research Council (2021-ERC-Advanced REMINDS Grant Nº 101054687), the Spanish Agencia Estatal de Investigación (PID2020-116844RB-C21 and CNS2022-135230) and the US NSF (ECCS-2151809, DMR-1828420).
References
[1] J. de Rojas et al., Nat. Commun. 11 (2020) 5871.
[2] J. de Rojas et al., Appl. Phys. Lett. 120 (2022) 070501.
[3] Z. Tan et al., Mater. Horiz. 10 (2023) 88.
[4] Z. Ma et al., Nat. Commun. 14 (2023) 6486.
