Voltage control of magnetism via magneto-ionics, where ion transport and/or redox processes drive magnetic modulation, holds great promise for next-generation memories and computing. This stems from its non-volatility and ability to precisely tune both the magnitude and speed of magnetic properties in a potential energy-efficient manner. However, expanding magneto-ionics to incorporate novel mobile ions or even multiple ion species is crucial for unlocking new phenomena and enabling multifunctional capabilities. Here, we demonstrate voltage-driven multi-ion transport in an FeBO system with increasing oxygen content, progressively transitioning from an electrostatic-like response to a more pronounced electrochemical (magneto-ionic) behavior. The voltage-driven transport of both B and Fe is activated by oxidation state tuning, owing to the larger electronegativity of oxygen. Such charge-transfer effects allow multi-ion magneto-ionics, where O ions move oppositely to Fe and B ions. These results pave the way for programmable functionalities by leveraging elements with different electron affinities through charge-transfer engineering.

In order to maximise electrochemically active surface area for water splitting, mesoporous Ni-Pt nanoparticles (NPs) are electrodeposited onto open-cell Ni foam to obtain a dual (macro- and meso-) porosity. Homogeneous deposition of the NPs is achieved by the use of a cylindrical Pt-coated mesh counter electrode, establishing a uniform electric field around the Ni foam substrate during electrodeposition. The Ni/Pt ratio is tunable with the electrodeposition parameters and all NPs are single-phase face-centred cubic solid solution and nanocrystalline, with a pore size of approx. 10 nm. Ni foam decorated with the Ni-rich particles, with mean particle sizes ranging from 50 to 80 nm, shows significantly higher activity at hydrogen evolution reaction (HER) in alkaline media with respect to the bare Ni foam. The highest HER efficiency was found fora relatively low Pt content of the NPs of about 26 at% (i. e., at 74 at% Ni) with an improvement of a factor 8 over bare Ni foam after durability assessment. These improvements are attributed to the higher surface area thanks to the NP structure, the dual porosity, and the alloying with Pt.

Rapid progress in information technologies has spurred the need for innovative memory concepts, for which advanced data-processing methods and tailor-made materials are required. Here we introduce a previously unexplored nanoscale magnetic object: an analog magnetic vortex controlled by electric-field-induced ion motion, termed magneto-ionic vortex or "vortion". This state arises from paramagnetic FeCoN through voltage gating and gradual N3-ion extraction within patterned nanodots. Unlike traditional vortex states, vortions offer comprehensive analog adjustment of key properties such as magnetization amplitude, nucleation/annihilation fields, or coercivity using voltage as an energy-efficient tuning knob. This manipulation occurs post-synthesis, obviating the need for energy-demanding methods like laser pulses or spin-torque currents. By leveraging an overlooked aspect of N3-magneto-ionics -- planar ion migration within nanodots -- precise control of the magnetic layer's thickness is achieved, which enables reversible transitions among paramagnetic, single-domain, and vortion states, offering future prospects for analog computing, multi-state data storage, or brain-inspired devices.

The oxygen reduction reaction (ORR) is one of the central points of research in proton exchange membrane fuel cells (PEMFC). A reduction of the Pt content of fuel cell electrodes is envisaged to lower their production cost, and the complete abandonment of Pt at the cathode by the use of Pt-free electrocatalysts is one of the many approaches to do so. The most developed Pt-free catalysts, M–N–C (where M is usually a transition metal) with atomically dispersed MN4 sites, are close to industrial requirements in terms of catalytic activity. Their major critical issue, a sufficient stability under operating conditions, can be effectively tackled by controlling the atomic configuration of the active sites.

The hydrogen evolution reaction at Ni foam electrodes is enhanced by magnetic fields of up to 12 kOe applied perpendicular to the electric field. While in 1 M KOH, the beneficial change in overpotential at an applied field is on the order of 10 mV, the effect increases drastically when the concentration of OH-is reduced to 0.1 M and 0.01 M, respectively, leading to a change in overpotential of up to 200 mV at the lowest concentration of OH-, making the reaction significantly more energy-efficient. The addition of KCl as a supporting electrolyte effectively suppresses adverse effects originating from the low conductivity of 0.01 M KOH while preserving the advantageous effects of the magnetic field. Finally, the effects are studied in neutral 1 M KCl, likewise leading to an improvement in HER of up to 200 mV in overpotential, and in filtered seawater, where the overpotential improves by 28 mV when applying 12 kOe. The effects of magnetic fields on HER are shown to be reversible, and scale with the magnitude of the field. In addition to chronopotentiometry at-10 mA where magnetic field pulses generate a pulse in the HER overpotential, measurements are complemented by linear sweep voltammetry and electrochemical impedance spectroscopy.

We introduce a nanocalorimetric technique based on microsecond-pulsed heating (μs-PHnC) that enables high-sensitivity, quasi-isothermal heat capacity measurements on nanoscale samples. Such resolution is critical for exploring thermodynamic signatures in low-dimensional materials, where conventional techniques fall short. By confining thermal excitation to microsecond timescales, this approach minimizes lateral heat diffusion, reduces heat capacity addenda to below 10^-9 J K^-1, and achieves noise densities as low as 75 pJ K^-1 Hz^-1/2 mm^-2, unlocking precise thermodynamic characterization of subnanogram samples in areas as small as 30 x 30 μm^2. The method delivers exceptional temperature homogeneity, as demonstrated by resolving sharp phase transitions, such as the antiferromagnetic transition in ultrathin CoO films, with unprecedented clarity. Its quasi-static operation is inherently compatible with external stimuli, including magnetic and electric fields, thereby expanding its utility for in-operando thermodynamic studies. This advancement establishes a robust and scalable platform for probing thermal phenomena in nanostructured and low-dimensional materials, significantly broadening the scope of nanocalorimetry.

The Big Data revolution has heightened the demand for robust, energy-efficient security hardware capable of withstanding increasingly sophisticated cyber threats. Conventional encryption schemes, reliant on complex algorithms, are resource-intensive and remain vulnerable. To fortify sensitive information, society needs innovative anti-hacking and anti-counterfeiting technologies that exploit new materials and designs. Here, we present a magneto-ionic strategy for hardware-level security based on fully selective voltage-controlled N3- ion migration within pre-defined, initially paramagnetic FeCoN dots. This process generates ferromagnetic sublayers of tuneable thickness, resulting in either deterministic (single-domain or vortex) or probabilistic states (with coexisting magnetic configurations and voltage-adjustable probabilities), each exhibiting stochastic orientation and chirality, thereby providing a rich platform for magnetic fingerprinting. This approach enables self-protected primitives, including true random number generators, physical unclonable functions, and in-memory probabilistic inference. The resulting reconfigurable architecture combines tamper resistance, low energy consumption, and scalability, marking a significant leap toward next-generation hardware security rooted in emergent magnetic phenomena.

Voltage-driven ion motion offers a powerful means to modulate magnetism and spin phenomena in solids, a process known as magneto-ionics, which holds great promise for developing energy-efficient next-generation micro- and nano-electronic devices. Synthetic antiferromagnets (SAFs), consisting of two ferromagnetic layers coupled antiferromagnetically via a thin non-magnetic spacer, offer advantages such as enhanced thermal stability, robustness against external magnetic fields, and reduced magnetostatic interactions in magnetic tunnel junctions. Despite its technological potential, magneto-ionic control of antiferromagnetic coupling in multilayers (MLs) has only recently been explored and remains poorly understood, particularly in systems free of platinum-group metals. In this work, room-temperature voltage control of Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions in Co/Ni-based SAFs is achieved. Transitions between ferrimagnetic (uncompensated) and antiferromagnetic (fully compensated) states is observed, as well as significant modulation of the RKKY bias field offset, emergence of additional switching events, and formation of skyrmion-like or pinned domain bubbles under relatively low gating voltages. These phenomena are attributed to voltage-driven oxygen migration in the MLs, as confirmed through microscopic and spectroscopic analyses. This study underscores the potential of voltage-triggered ion migration as a versatile tool for post-synthesis tuning of magnetic multilayers, with potential applications in magnetic-field sensing, energy-efficient memories and spintronics.

Control of magnetism through voltage-driven ionic processes (i.e., magneto-ionics) holds potential for next-generation memories and computing. This stems from its non-volatility, flexibility in adjusting the magnitude and speed of magnetic modulation, and energy efficiency. Since magneto-ionics depends on factors like ionic radius and electronegativity, identifying alternative mobile ions is crucial to embrace new phenomena and applications. Here, the feasibility of C as a prospective magneto-ionic ion is investigated in a Fe-C system by electrolyte gating. In contrast to most magneto-ionic systems, Fe-C presents a dual-ion mechanism: Fe and C act as cation and anion, respectively, moving uniformly in opposite directions under an applied electric field. This leads to a 7-fold increase in saturation magnetization with magneto-ionic rates larger than 1 emu cm-3 s-1, and a 25-fold increase in coercivity. Since carbides exhibit minimal cytotoxicity, this introduces a biocompatible dimension to magneto-ionics, paving the way for the convergence of spintronics and biotechnology.

Titanium and its alloys are widely used for implants, although they have limitations like higher elastic modulus compared to bone, causing stress shielding and potential implant failure. To address these issues, beta-Ti alloys and calcium phosphate coatings are being developed to improve the mechanical properties while enhancing bone integration. The risk of infection is another important limitation that can be addressed through the deposition of antibacterial and antibiofilm coatings on the alloys. Here, we present a beta-Ti alloy (Ti-18Mo-6Nb-5Ta (wt %)) coated with calcium-deficient hydroxyapatite (CDHA) and decorated with silver nanoparticles intended to be used as antimicrobial orthopedic implants. The experiments revealed that human osteoblasts were able to adhere and proliferate on coating. The presence of silver nanoparticles did not adversely affect human osteoblast differentiation and led to a 50 % increase in type I collagen production. The coating decorated with silver nanoparticles exhibited a significant antibacterial effect against Staphylococcus aureus, reducing biofilm formation by over 40 % after 24 h compared to the undecorated coating. Taken together, these results show the effectiveness of the silver decorated CDHA coating in enhancing osteoblasts proliferation and differentiation while also reducing biofilm growth when compared to CDHA coating.

Magneto-ionics, which refers to the modification of the magnetic properties of materials through electric-field-induced ion migration, is emerging as one of the most promising methods to develop nonvolatile energy-efficient memory and spintronic and magnetoelectric devices. Herein, the controlled generation of ferromagnetism from paramagnetic Co-Ni oxide patterned microdisks (prepared upon thermal oxidation of metallic microdisks with dissimilar Co-Ni ratios, i.e., Ni25Co75 and Ni50Co50) is demonstrated under the action of voltage. The effect is related to the partial reduction of the oxide phases to their metallic forms. Samples richer in Co show stronger magneto-ionic activity, which manifests in lower-onset threshold voltages, faster switching rates, and larger values of the attained saturation magnetization. By means of scanning electron microscopy, a cobalt segregation phenomenon has been experimentally observed upon thermal oxidation, which has been theoretically discussed from the diffusivities' viewpoint. X-ray diffraction characterization has revealed transitions between purely mixed Ni and Co oxides, in the OFF state, to a mixture of oxide and metallic phases, in the ON state, because of the oxygen ion motion outward/inward the Co-Ni oxide microdisks, depending on the voltage polarity. Ab initio calculations reveal that the energy barrier for oxygen vacancy migration is lower in CoO than in NiO, in agreement with the obtained magneto-ionic responses. The observation of magneto-ionic effects in patterned disks (and not only in archetypical continuous films) is a step further for the practical utilization of this phenomenon in real miniaturized devices.

As traditional complementary metal–oxide–semiconductor scaling approaches its physical limits, the search for alternative computing paradigms has led to renewed interest in magnetic materials, not merely as passive memory units but also as active components in computation itself. Emerging concepts employ spin dynamics, topological magnetic textures, magneto-ionic control, or magnonics for advanced data and signal processing applications, including neuromorphic, reservoir, or quantum-inspired computing. Recent breakthroughs, such as skyrmion-based logic, antiferromagnetic spintronics, or magnon-mediated signal processing, highlight the growing potential of magnetic materials. Ideas such as stochastic magnetic neurons, magnon-based reservoirs, or voltage-controlled reconfigurability further illustrate the rapid evolution of this research area. Innovation in this field requires new interdisciplinary joint efforts in aspects such as materials discovery, device integration, and the development of robust theoretical frameworks. By integrating advances across these domains, magnetic materials are well positioned to play a central role in next-generation intelligent computing.

Switchability of materials properties by applying controlled stimuli such as voltage pulses is an emerging field of study with applicability in adaptive and programmable devices like neuromorphic transistors or non-emissive smart displays. One of the most exciting approaches to modulate materials performance is mobile ion/vacancy insertion for inducing changes in relevant electrical, optical, or magnetic properties, among others. Unveiling the interplay between changes in the concentration of mobile defects (like oxygen vacancies) and functional properties in relevant materials represents a step forward for underpinning the emerging oxide iontronics discipline. In this work, electrochemical oxide-ion pumping cells were fabricated for an analog control of the oxygen stoichiometry in thin films of mixed ionic-electronic conductor La0.5Sr0.5FeO3-δ. We demonstrate over more than 4 orders of magnitude electronic conductivity control within the same crystallographic phase through the precise and continuous voltage control of the oxygen stoichiometry. We show that behind the modification of the transport properties of the material lays a paramagnetic-to-antiferromagnetic transition. We exploit such magnetoelectric coupling to show control over the exchange interaction between La0.5Sr0.5FeO3-δ and a ferromagnetic Co layer deposited on top.

Switchability of materials properties by applying controlled stimuli such as voltage pulses is an emerging field of study with applicability in adaptive and programmable devices like neuromorphic transistors or non-emissive smart displays. One of the most exciting approaches to modulate materials performance is mobile ion/vacancy insertion for inducing changes in relevant electrical, optical, or magnetic properties, among others. Unveiling the interplay between changes in the concentration of mobile defects (like oxygen vacancies) and functional properties in relevant materials represents a step forward for underpinning the emerging oxide iontronics discipline. In this work, electrochemical oxide-ion solid-state pumping cells were fabricated for analog control of the oxygen stoichiometry in thin films of mixed ionic-electronic conductor La0.5Sr0.5FeO3-delta. We demonstrate over more than four orders of magnitude electronic conductivity control at 50 degrees C within the same crystallographic phase through precise and continuous voltage control of the oxygen stoichiometry. We show that behind the modification of the transport properties of the material lays a paramagnetic-to-antiferromagnetic transition. We exploit such magnetoelectric coupling to show control over the exchange interaction between La0.5Sr0.5FeO3-delta and a ferromagnetic Co layer deposited on top.

Ferroelectric doped hafnium oxide constitutes, at present, an intensively investigated candidate material to develop outperforming non-volatile memory devices. We report reading and writing of the ferroelectric polarization with light in Hf0.5Zr0.5O2/Nb:SrTiO3 structures, where light is absorbed at the interface between the two materials, thereby enabling both processes. Reading of ferroelectric polarization is accomplished through the induced short-circuit photocurrents, which is a pathway towards voltage-less-non-destructive reading. Optical writing allows remote and contact-less switching of ferroelectric polarization, without the need for external voltages. The presence or absence of a Pt capping layer is crucial for the aforementioned read/write operations. If top Pt is present, photocarriers flow, resulting in short-circuit photocurrent, whose magnitude is modulated by the induced depolarization field. Instead, if Pt is removed, photocarriers are accumulated at the top surface, eventually producing an optically induced switching of polarization, as revealed by piezoelectric force microscopy observations. These results are highly appealing for the design of novel energy-efficient ferroelectric memory devices actuated with light.

Optical means instead of electric fields may offer a new pathway for low-power and wireless control of magnetism, holding great potential to design next-generation memory and spintronic devices. Artificial multiferroic materials have shown remarkable suitability as platforms towards the optical control of magnetic properties. However, the practical use of magnetic modulation should be both stable and reversible and, particularly, it should occur at room temperature. Here we show an unprecedented reversible modulation of magnetism using low-intensity visible-light in Fe75Al25/BaTiO3 heterostructures, at room temperature. This is enabled by the existence of highly oriented charged domain walls arranged in arrays of alternating in-plane and out-of-plane ferroelectric domains with stripe morphology. Light actuation yields a net anisotropic stress caused by ferroelectric domain switching, which leads to a 90-degree reorientation of the magnetic easy axis. Significant changes in the coercivity and squareness ratio of the hysteresis loops can be light-modulated, encouraging the development of novel low energy-consumption wireless magneto-optical devices.

The increasing energy demand in information technologies requires novel low-power procedures to store and process data. Magnetic materials, central to these technologies, are usually controlled through magnetic fields or spin-polarized currents that are prone to the Joule heating effect. Magneto-ionics is a unique energy-efficient strategy to control magnetism that can induce large non-volatile modulation of magnetization, coercivity and other properties through voltage-driven ionic motion. Recent studies have shown promising magneto-ionic effects using nitrogen ions. However, either liquid electrolytes or prior annealing procedures are necessary to induce the desired N-ion motion. In this work, magneto-ionic effects are voltage-triggered at room temperature in solid state systems of CoxMn1-xN films, without the need of thermal annealing. Upon gating, a rearrangement of nitrogen ions in the layers is observed, leading to changes in the co-existing ferromagnetic and antiferromagnetic phases, which result in substantial increase of magnetization at room temperature and modulation of the exchange bias effect at low temperatures. A detailed correlation between the structural and magnetic evolution of the system upon voltage actuation is provided. The obtained results offer promising new avenues for the utilization of nitride compounds in energy-efficient spintronic and other memory devices.

A fundamental study regarding the electrochemical synthesis of composite coatings with application in the or-thopaedic field has been conducted. In particular, the electrodeposition of calcium phosphate coatings with Ag nanoparticles (AgNPs) from either a single electrolyte (one-step, 1S) or two electrolytes (two-step, 2S) on a beta-Ti alloy (Ti-18Mo-6Nb-4Ta in wt%) was investigated. Pulse current deposition was implemented to produce the composite coatings by the 1S approach from a simple solution containing 42 mM Ca(NO3)2Greek ano teleia4H2O, 25 mM NH4H2PO4, and 0.5 mM AgNO3 at 65 degrees C. Meanwhile, the calcium phosphate matrix was also deposited by pulse current, and Ag was afterwards grown by direct current from 0.1 M KNO3 + x mM AgNO3 (x = 5, 10) at 25 degrees C (2S approach). The Ca/P ratio of the matrix was compatible with the formation of calcium-deficient hydroxyapatite (CDHA). The resulting Ag content in the composites could be varied between 4 and 13 wt% as a function of the working conditions. The 2S-derived coatings produced by electroplating Ag at j = -20.8 mA/cm2 from 0.1 M KNO3 + 10 mM AgNO3 furnished an optimal dispersion of the AgNPs on top of the CDHA matrix, while ag-gregation and/or dendritic growth was observed in other cases. Glow discharge optical emission spectrometry (GDOES) measurements indicated that a given amount of AgNPs becomes engulfed in the CDHA matrix during the 1S electrodeposition, whereas most of them decorate its outer surface in the 2S-derived coatings. The applicability of the two approaches was extended to the case of zinc oxide. ZnO-containing CDHA coatings in which the Zn element was homogeneously distributed across the film surface were obtained from 42 mM Ca (NO3)2Greek ano teleia4H2O, 25 mM NH4H2PO4 and 1 mM Zn(NO3)2Greek ano teleia6H2O at 65 degrees C (1S approach). On the contrary, ZnO-NPs could be clearly observed when deposition from 5 mM KNO3 + 5 mM Zn(NO3)2 was performed at 70 degrees C on top of previously grown CDHA (2S approach). The results indicated that the percentage and location of the antibac-terial element (Ag, Zn) in the calcium phosphate matrix can be tuned on demand to a great extent by electro-chemical means.

Magnetoelectric multiferroics, either single-phase or composites comprising ferroelectric/ferromagnetic coupled films, are promising candidates for energy efficient memory computing. However, most of the multiferroic magnetoelectric systems studied so far are based on materials that are not compatible with industrial processes. Doped hafnia is emerging as one of the few CMOS-compatible ferroelectric materials. Thus, it is highly relevant to study the integration of ferroelectric hafnia into multiferroic systems. In particular, ferroelectricity in hafnia, and the eventual magnetoelectric coupling when ferromagnetic layers are grown atop of it, are very much dependent on quality of interfaces. Since magnetic metals frequently exhibit noticeable reactivity when grown onto oxides, it is expected that ferroelectricity and magnetoelectricity might be reduced in multiferroic hafnia-based structures. In this article, we present excellent ferroelectric endurance and retention in epitaxial Hf0.5Zr0.5O2 films grown on buffered silicon using Co as the top electrode. The crucial influence of a thin Pt capping layer grown on top of Co on the ferroelectric functional characteristics is revealed by contrasting the utilization of Pt-capped Co, non-capped Co and Pt. Magnetic control of the imprint electric field (up to 40% modulation) is achieved in Pt-capped Co/Hf0.5Zr0.5O2 structures, although this does not lead to appreciable tuning of the ferroelectric polarization, as a result of its high stability. Computation of piezoelectric and flexoelectric strain-mediated mechanisms of the observed magnetoelectric coupling reveal that flexoelectric contributions are likely to be at the origin of the large imprint electric field variation.

A Pt skin effect, i.e., an enrichment of Pt within the first 1-2 nm from the surface, is observed in as-prepared electrodeposited Ni-rich Ni-Pt thin films. This effect, revealed by Rutherford backscattering (RBS), is present for both dense thin films and mesoporous thin films synthesized by micelle-assisted electrodeposition from a chloride-based electrolyte. Due to the Pt skin effect, the Ni-rich thin films show excellent stability at the hydrogen evolution reaction (HER) in acidic media, during which a gradient in the Pt/Ni ratio is established along the thickness of the thin films, while the activity at the HER remains unaffected by this structural change. Further characterization by elastic recoil detection with He ions analysis shows that hydrogen profiles are similar to those of Pt: a surface hydrogen peak coincides with the Pt skin, and a gradient in hydrogen concentration is established during HER in acidic media, together with a considerable uptake in hydrogen. A comparative study shows that in alkaline media, hydrogen evolution has little to no effect on the structural properties of the thin films, even for much longer times of exposure. The mesoporous thin films, in addition to their higher efficiency at HER compared to dense thin films, also show lower internal stress, as determined by Rietveld refinement of grazing incidence X-ray diffraction patterns. The latter also reveal a fully single-phase and nanocrystalline structure for all thin films with varying Ni contents.