Luis E. Hueso

The generation and transport of spin currents are central to spintronics, a technologically relevant field in which information is carried and manipulated using the electron spin rather than solely the electrical charge. Conventionally, electrical spin injection and the separation of charge and spin currents rely either on ferromagnets^1-10, in which spin polarization originates from a net magnetization, or on relativistic effects such as the spin Hall effect^11-16. Here we demonstrate spin injection from Mn₅Si₃, a compensated magnet with vanishing net magnetization. Using lateral spin-valve devices, we electrically inject spins from Mn₅Si₃ into a non-magnetic channel and detect their propagation at a spatially separated ferromagnetic electrode. Switching between time-reversed magnetic states of Mn₅Si₃ reverses the detected spin signal, demonstrating that the spin injection breaks time-reversal symmetry. This behaviour is observed for two distinct electrical-biasing geometries, providing a characteristic signature that differs from conventional ferromagnetic and spin-Hall injection. Symmetry analysis, first-principles calculations and spin-transport modelling show that our observations are consistent with the altermagnetic order of Mn₅Si₃, in which spin-polarized currents can arise despite the absence of net magnetization^17-21. The calculations yield spin polarizations of 6.5-10%, comparable to those of conventional ferromagnets, whereas the spin-transport modelling of the experiments indicates spin diffusion lengths of 50-130 nm. Our results provide experimental evidence that a compensated magnet can generate spin currents controlled by its magnetic order and demonstrate that the altermagnetic properties of Mn₅Si₃ enable spintronic functionality without net magnetization.

Spin–charge interconversion provides the essential link between spin information and electrical signals in spintronic devices. In spin–orbit coupled systems, spin–charge interconversion can contain multiple components associated with different spin-polarization directions, reflecting the underlying spin texture. Tuning this spin texture, therefore, provides a way to control not only the magnitude of spin–charge interconversion but also the balance among its different components. Graphene-based van der Waals heterostructures provide an attractive platform for this purpose because interfacial spin–orbit coupling can host multiple spin–charge interconversion channels that couple to different spin-polarization directions. Here, we demonstrate electric-field control of spin texture in a dual-gated HfS2/graphene van der Waals heterostructure, where independent control of carrier density and vertical electric field allows us to disentangle electrostatic doping from electric field-induced spin–orbit effects. Nonlocal spin precession measurements show that, near zero vertical electric field, spin–charge interconversion is dominated by a spin Hall component with out-of-plane spins. Increasing the vertical electric field enhances additional in-plane spin components with Rashba–Edelstein-like character, including contributions both parallel and perpendicular to the charge current. These results provide experimental evidence that a vertical electric field can reconfigure the effective spin texture and control the corresponding spin–charge interconversion components, demonstrating electrical tunability of spin–orbit functionalities.

Realizing the potential of oxide-based memristive devices for high-density data storage and energy-efficient computing still relies on overcoming key technical challenges, including the need for a larger number of stable resistance states, faster switching speeds, lower SET/RESET voltages, improved endurance, and reduced variability. Addressing these limitations requires innovative material design strategies. Here, we demonstrate that introducing a thin layer of oxide-ion conductor SrCoO3–x between the metal and the SrTiO3-based memristive elements, expands the number of distinguishable resistance states from ≈8 to ≈22. This modification also reduced the SET/RESET voltage by 50% and markedly improved device endurance, albeit with a trade-off of reduced state retention. To assess the performance of this architecture, we trained a two-layer fully connected neural network using the experimental SrTiO3/SrCoO3–x memristor characteristics on the MNIST handwritten digit dataset. Networks with hidden-layer sizes between 64 and 256 neurons achieved classification errors below 7%. Finally, we confirmed the transferability of this interface-engineering approach by applying it to HfOx-based devices, achieving a consistent enhancement in the resistive state window.

Metal halide perovskite solar cells have achieved remarkable laboratory-scale efficiencies, but their commercialization requires processing strategies that are reproducible, scalable, sustainable, and broadly applicable. Here, we introduce a static antisolvent treatment applied after film deposition. By incorporating isopropanol into a conventional low-polarity antisolvent, we accelerate and homogenize perovskite crystallization through enhanced polarity and improved interaction with precursors and deposition solvents. In situ grazing-incidence wide-angle X-ray scattering and photoluminescence reveal the formation of larger, more uniformly distributed crystalline nanodomains during static treatment with the binary antisolvent. The method is effective for four perovskite compositions under 30% relative humidity, and replacing aromatic antisolvents with eco-friendly ethyl acetate preserves film quality while improving sustainability. We further validate the approach in 25 cm² single-junction minimodules and perovskite/silicon tandem devices, achieving power conversion efficiencies of 18.1% and 27.7%, respectively. Taken together, these findings provide a scalable and sustainable route for the fabrication of perovskite photovoltaics.

Metal thiophosphates are emerging as a multifunctional material platform for neuromorphic electronics due to their accessible polar phases and ion dynamics on biologically relevant timescales. While resistive switching in these materials is frequently attributed to ferroelectric or antiferroelectric polarization, the intrinsic role of ion dynamics remains underexplored. Here, we isolate and demonstrate interfacial resistive switching driven purely by ionic hopping in paraelectric CuCrP2S6. Robust and reproducible resistive switching is observed in the absence of measurable ferroelectricity. The conductance can be tuned through both voltage amplitude and sweep rate, revealing a rate dependence characteristic of ion dynamics. The resulting resistance states exhibit controllable volatility, where the switching rate determines the decay time constant of the readout current, attributed to ionic relaxation. Using either inert or reactive electrodes, we observe electrical evidence of solid-state redox activity associated with the interfacial reduction of native Cu+ ions, enabling the controlled formation of filamentary conduction pathways. Analysis of this process allows the extraction of the Cu+ diffusion coefficient, providing quantitative insight into the underlying transport kinetics. The understanding of ionic-redox-based resistive switching in CuCrP2S6 is crucial for unleashing its full potential as a material platform for dual- or multi-mode operation.

The efficient detection of spin currents is crucial for the development of next-generation spintronic devices. Here, we demonstrate that ultrathin W layers, with thicknesses down to 2 nm — equivalent to only four atomic planes — allow for highly efficient spin-to-charge conversion. From spin pumping experiments in YIG/W bilayers, we analyzed the inverse spin Hall effect voltage dependence on W thickness and extracted a spin Hall conductivity of σ _SH = -1.14(6) ×10 ⁵ Ω ^-1 m ^-1 , yielding effective spin Hall angles ranging from -0.27(4) to -0.88(4) over the investigated thickness range. Furthermore, assuming the Elliott-Yafet spin scattering mechanism dominates, we estimate a spin diffussion length λ _sd = 4.3(5)×10 ^-15 Ω m ² ^2 / ρ _W , where the W resistivity ρ _W is strongly dependent on thickness. Structural characterization, together with room-temperature electrical resistivity measurements and the high spin-to-charge conversion efficiency observed, confirms the stabilization of the β-phase in these ultrathin W layers. We demonstrate that the monotonic increase of the inverse spin Hall effect voltage with decreasing W thickness persists down to 2-nm-thick W layer, reflecting the extremely short spin diffusion length. This allows for efficient spin-current detection in W layers below 5 nm, effectively doubling the voltage output at half the thickness. In the thinnest sample, a continuous 2-nm-thick W layer, the generated voltage exceeds 0.5 mV—well within the operating range of conventional electronics. These findings demonstrate not only the feasibility of spin-current detection in ultrathin W, but also its compatibility with conventional electronics. They highlight the strong potential of integrating ultrathin W layers with high-quality YIG films for the development of energy-efficient spintronic devices and sensors.

We fabricated a C60-based molecular spin photovoltaic device that integrated a photovoltaic response with the spin transport across the molecular layer. The photovoltaic response can be modified under the application of a small magnetic field, with a magnetophotovoltage of up to 5% at room temperature. Device functionalities include a magnetic current inverter and the presence of diverging magnetocurrent at certain illumination levels that could be useful for sensing. Completely spin-polarized currents could be created by balancing the external partially spin polarized injection with the photogenerated carriers.

Understanding the interplay between magnetic ordering and light emission is crucial for developing magneto‐optical technologies. However, this phenomenon is poorly understood since observations of this coupling vary significantly across materials. In this context, hybrid organic‐inorganic metal halide perovskites (HOIPs) that incorporate Mn ²⁺ ions are a chemically and structurally tunable platform for exploring this phenomenon, since they exhibit magnetic ordering and photoluminescence (PL) emission. Here, two antiferromagnetic Mn‐based HOIPs with different organic cations are studied, resulting in distinct lattice stiffness, Mn ²⁺ ‐Mn ²⁺ distance, and octahedral distortion. Temperature‐dependent PL excitation spectroscopy reveals changes in crystal field splitting energy and Racah parameters well above the Néel temperature (T _N ), indicating the emergence of Mn ²⁺ ‐Mn ²⁺ magnetic interactions prior to reach long‐range magnetic ordering. These variations align with the observed changes in temperature‐PL evolution. The compound with a more rigid lattice shows stronger changes closer to T _N , suggesting combined effects of magnetic polarons and spin‐canting. In contrast, magnetic modifications induced by magnetic polarons prevail in the HOIP with a softer lattice. These results reveal the complexity of the magneto‐optical coupling in Mn‐based HOIPs and provide new insights into this field extensible to other 2D materials that exhibit this phenomenon with potential for advanced magneto‐optical applications.

IPA facilitates FA ⁺ redistribution, thereby promoting a more homogeneous distribution of Cs ⁺ throughout the film and, consequently, enabling uniform and complete conversion to the α-phase.