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Synthetic antiferromagnets with perpendicular magnetic anisotropy (PMA-SAFs) have gained growing attention for both conventional and next-generation spin-based technologies. While the progress of PMA-SAF spintronic devices on rigid substrates has been remarkable, only few examples of flexible thin-film heterostructures are reported in the literature, all containing platinum group metals (PGMs). Systems based on Co/Ni may offer additional advantages with respect to devices containing PGMs, i.e., low damping and high spin polarization. Moreover, limiting the use of PGMs may relieve the demand for critical raw materials and reduce the environmental impact of related technologies, thus contributing to the transition toward a more sustainable future. Here, we discuss for the first time the realization of Co/Ni-based PMA-SAFs on polymer tapes and exploit it to obtain flexible giant magneto-resistive spin valves (GMR-SVs) with perpendicular magnetic anisotropy. Several combinations of buffer and capping layers (i.e., Pt, Pd, and Cu/Ta) are also investigated. High-quality flexible SAFs with a fully compensated antiferromagnetic region and SVs with a sizable GMR ratio (up to 4.4%), in line with the values reported in the literature for similar systems on rigid substrates, were obtained in all cases. However, we demonstrate that PGMs allows achieving the best results when used as a buffer layer, while Cu is the best choice as a capping layer to optimize the properties of the stacks. We justify the role of buffer and capping layers in terms of different interdiffusion mechanisms occurring at the interface between the metallic layers. These results, along with the high robustness of the samples' properties against bending (up to 180°), indicate that complex and bendable Co/Ni-based heterostructures with reduced content of PGMs can be obtained on flexible tapes, allowing for the development of novel flexible and sustainable spintronic devices for applications in many fields including wearable electronics, soft robotics, and biomedicine.

The development of spintronic devices has been limited by the poor compatibility between semiconductors and ferromagnetic sources of spin. The broken inversion symmetry of some semiconductors may allow for spin–charge interconversion, but its control by electric fields is volatile. This has led to interest in ferroelectric Rashba semiconductors, which combine semiconductivity, large spin–orbit coupling and non-volatility. Here we report room-temperature, non-volatile ferroelectric control of spin-to-charge conversion in epitaxial germanium telluride films. We show that ferroelectric switching by electrical gating is possible in germanium telluride, despite its high carrier density. We also show that spin-to-charge conversion has a similar magnitude to what is observed with platinum, but the charge current sign is controlled by the orientation of ferroelectric polarization. Comparison between theoretical and experimental data suggests that the inverse spin Hall effect plays a major role in switchable conversion. The ferroelectric polarization of epitaxial thin films of germanium telluride can be switched by electrical gating and used to control spin-to-charge conversion.

Flexible magneto-resistive heterostructures have received a great deal of attention over the past few years as they allow for new product paradigms that are not possible with conventional rigid substrates. While the progress and development of systems with longitudinal magnetic anisotropy on non-planar substrates has been remarkable, flexible magneto-resistive heterostructures with perpendicular magnetic anisotropy (PMA) have never been studied despite the possibility to obtain additional functionality and improved performance. To fill this gap, flexible PMA Co/Pd-based giant magneto-resistive (GMR) spin-valve stacks were prepared by using an innovative transfer-and-bonding strategy exploiting the low adhesion of a gold underlayer to SiOx/Si(100) substrates. The approach allows overcoming the limits of the direct deposition on commonly used polymer substrates, whose high surface roughness and low melting temperature could hinder the growth of complex heterostructures with perpendicular magnetic anisotropy. The obtained PMA flexible spin-valves show a sizeable GMR ratio (∼1.5%), which is not affected by the transfer process, and a high robustness against bending as indicated by the slight change of the magneto-resistive properties upon bending, thus allowing for their integration on curved surfaces and the development of a novel class of advanced devices based on flexible magneto-resistive structures with perpendicular magnetic anisotropy. Besides endowing the family of flexible electronics with PMA magneto-resistive heterostructures, the exploitation of the results might apply to high temperature growth processes and to the fabrication of other functional and flexible multilayer materials engineered at the nanoscale.

Although metal/ferroelectric/semiconductor tunnel junctions have been attracting widespread interest as next-generation memory devices, only limited effort has been devoted so far to quantitatively address their current–voltage characteristics and their achievable memory window. In this article, we show experimental data on template Pt/BaTiO3/Nb:SrTiO3 tunnel junctions confirming, first of all, that large memory windows can be achieved in these devices when the switching of the electric polarization in the ferroelectric layer moves the substrate between an accumulation and a depletion condition. Besides, by measuring the current–voltage curve of the devices quickly after the set/reset pulses used for polarization switching, the importance of considering the detrimental effects of the large depolarization fields in the ferroelectric layer when assessing the device memory window is demonstrated. The experimental data are, then, reproduced by a model for electron transport through the junction accounting for both drift/diffusion and distributed tunneling in the semiconductor. The model allows to catch a comprehensive physical picture of device operation and represents a powerful tool for the design and optimization of ferroelectric tunnel junctions with semiconductor electrodes.

Since the 1980s, the generation and detection of spin currents has relied on ferromagnets. Their switching today relies on spin-orbit torque from heavy metals. Nevertheless, spin injection in semiconductors has rather low efficiency. Ferroelectric Rashba semiconductors (FERSC) [1,2] may constitute a new paradigm for semiconductor spintronics, thanks to the combination of semiconductivity, large spin-orbit interaction, and the non-volatility provided by ferroelectricity. Here we report the room-temperature ferroelectric switching of spin-to-charge conversion in epitaxial GeTe films. We first show that ferroelectricity in GeTe can be reversed by electrical gating despite its high carrier density. Then, we reveal a spin-to-charge conversion as effective as in Pt, but whose sign switches with the ferroelectric polarization. These results open a route towards devices combining spin-logic and memory integrated into a silicon-compatible material.

Ethylene glycol-based solutions containing metal precursor chloride salts were investigated for the electrodeposition of cobalt thin films and nanowires. The electrochemical behavior of 0.5 M Co(II) chloride solution at 70 °C was studied by means of cyclic voltammetry (CV) on a Pt substrate. The reduction process was shown to be irreversible, with high faradaic efficiencies (85–90 %). A diffusion coefficient (D0) of 2.29 × 10−6 cm2 s−1 for the Co species was estimated from the electrochemical behavior at different scan rates (from 25 to 125 mV s−1). The electrodeposition process was also studied on a copper substrate at different cathodic potentials (from −0.75 V vs Pt to −0.95 V vs Pt). Field-emission scanning electron microscopy (FE-SEM) and electron dispersive spectroscopy (EDS) revealed high-purity, compact films. Template-assisted electrodeposition resulted in ~16–18 μm long cobalt nanowires with an aspect ratio L/D > 100. X-ray diffraction (XRD) analysis of Co thin films showed a preferential orientation along the HCP [100] direction, which was even more marked for the nanowires. Vibrating sample magnetometry (VSM) highlighted that the fact that Co thin films were magnetized in-plane, while in nanowires a competition between shape and magnetocrystalline anisotropy led to similar magnetic behavior for the in-plane and out-of-plane directions. Keywords: Organic solvent, Magnetization, Non-aqueous, Electroplating, Alumina template

Lead-free piezoceramics aiming at replacing the market-dominant Pb(ZrxTi1−x)O3 have been extensively researched for more than a decade worldwide due to the toxicity of lead. In this context, (K0.5Na0.5)NbO3 (KNN) triggered the attention of the scientific community thanks to its bulk record piezoelectric coefficient combined with high critical temperature, which make it a good candidate for applications. In this paper, (001)-oriented KNN thin films grown by pulsed laser deposition on Pt(111)/TiO2/SiO2/Si substrates are investigated. We highlight the relevance of the template substrate in determining the structure of the film. Developing a suitable treatment for the Pt substrate is of great importance to film morphologic and topographic quality and to electric, ferroelectric, and piezoelectric properties. From local characterization of piezoelectric properties, we find a piezoelectric coefficient d33 of about 80 pm/V, comparable to the highest values reported for state-of-the-art undoped KNN thin films. Finally, electrical characterization of fabricated micro-capacitors allows the investigation of dielectric performance and shows remanent ferroelectric polarization over microscopic areas, thus paving the way to the integration of these KNN films in microfabricated actuator devices.

Artificial magnetoception is a new and yet to be explored path for humans to interact with our surroundings. This technology is enabled by thin film magnetic field sensors embedded in a soft and flexible format to constitute magnetosensitive electronic skins (e-skins). Being limited by the sensitivity to in-plane magnetic fields, magnetosensitive e-skins are restricted to basic proximity and angle sensing and are not used as switches or logic elements of interactive wearable electronics. Here, we demonstrate a novel magnetoreceptive platform for on-skin touchless interactive electronics based on flexible spin valve switches with the sensitivity to out-of-plane magnetic fields. The technology relies on all-metal Co/Pd-based spin valves with a synthetic antiferromagnet possessing perpendicular magnetic anisotropy. The flexible magnetoreceptors act as logic elements, namely momentary and permanent (latching) switches. The switches maintain their performance even upon severe bending to a radius of less than 5 mm and withstand repetitive bending for hundreds of cycles. We integrated flexible switches in on-skin interactive electronics and demonstrated their performance as touchless human-machine interfaces, which are intuitive to use, energy efficient, and insensitive to external magnetic disturbances. This technology offers qualitatively new functionalities for electronic skins and paves the way towards full-fledged on-skin touchless interactive electronics.

A ferromagnetic (FM) thin film deposited on a substrate of $\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}){\mathrm{O}}_{3}\text{\ensuremath{-}}{\mathrm{PbTiO}}_{3}$ (PMN-PT) is an appealing heterostructure for the electrical control of magnetism, which would enable nonvolatile memories with ultralow-power consumption. Reversible and electrically controlled morphological changes at the surface of PMN-PT suggest that the magnetoelectric effects are more complex than the commonly used ``strain-mediated'' description. Here we show that changes in substrate morphology intervene in magnetoelectric coupling as a key parameter interplaying with strain. Magnetic-sensitive microscopy techniques are used to study magnetoelectric coupling in Fe/PMN-PT at different length scales, and compare different substrate cuts. The observed rotation of the magnetic anisotropy is connected to the changes in morphology, and mapped in the crack pattern at the mesoscopic scale. Ferroelectric polarization switching induces a magnetic field-free rotation of the magnetic domains at micrometer scale, with a wide distribution of rotation angles. Our results show that the relationship between the rotation of the magnetic easy axis and the rotation of the in-plane component of the electric polarization is not straightforward, as well as the relationship between ferroelectric domains and crack pattern. The understanding and control of this phenomenon is crucial to develop functional devices based on FM/PMN-PT heterostructures.

Malaria remains the most important mosquito‐borne infectious disease worldwide, with 229 million new cases and 409.000 deaths in 2019. The infection is caused by a protozoan parasite which attacks red blood cells by feeding on hemoglobin and transforming it into hemozoin. Despite the WHO recommendation of prompt malaria diagnosis, the quality of microscopy‐based diagnosis is frequently inadequate while rapid diagnostic tests based on antigens are not quantitative and still affected by non‐negligible false negative/positive results. PCR‐based methods are highly performant but still not widely used in endemic areas. Here, a diagnostic tool (TMek), based on the paramagnetic properties of hemozoin nanocrystals in infected red blood cells (i‐RBCs), is reported on. Exploiting the competition between gravity and magnetic forces, i‐RBCs in a whole blood specimen are sorted and electrically detected in a microchip. The amplitude and time evolution of the electrical signal allow for the quantification of i‐RBCs (in the range 10–105 i‐RBC µL−1) and the distinction of the infection stage. A preliminary validation study on 75 patients with clinical suspect of malaria shows on‐field operability, without false negative and a few false positive results. These findings indicate the potential of TMek as a quantitative, stage‐selective, rapid test for malaria., Malaria is caused by the Plasmodium parasite which feeds on hemoglobin and produces paramagnetic hemozoin crystals within red blood cells (RBCs). A quantitative and stage‐selective pan‐malaria diagnostic test is disclosed, based on a simple concept implemented on a microchip: the sorting and electrical detection of infected RBCs, thanks to the competition between magnetic and gravity forces.

Synthetic antiferromagnets (SAF) are widely used for a plethora of applications among which data storage, computing, and in the emerging field of magnonics. In this framework, controlling the magnetic properties of SAFs via localized thermal treatments represents a promising route for building novel magnonic materials. In this paper, we study via vibration sample magnetometry the temperature dependence of the magnetic properties of sputtered exchange bias SAFs grown via magnetron sputtering varying the ferromagnetic layers and spacer thickness. Interestingly, we observe a strong, reversible modulation of the exchange field, saturation field, and coupling strength upon heating up to 250 &deg, C. These results suggest that exchange bias SAFs represent promising systems for developing novel artificial magnetic nanomaterials via localized thermal treatment.

Large spin Hall angles have been observed in 3d ferromagnets, but their origin, and especially their link with the ferromagnetic order, remain unclear. Here, we investigate the inverse spin Hall effect of Ni60Cu40 and Ni50Cu50 across their Curie temperature using spin pumping experiments. We evidence that the inverse spin Hall effect in these samples is comparable to that of platinum, and that it is insensitive to the magnetic order. These results points towards a Heisenberg localized model of the transition, and suggest that the large spin Hall effects in 3d ferromagnets can be independent of the magnetic phase., 3 figures

When coupled with ferromagnetic (FM) layers, topological insulators (TI) are expected to boost the charge-to-spin conversion efficiency across the FM/TI interface. In this context, a thorough control and optimization of the FM/TI interface quality are requested. In this paper, the evolution of the chemical, structural, and magnetic properties of the Fe/Sb2Te3 heterostructure, as a function of a rapid mild (up to 200 °C) thermal annealing conducted on the Sb2Te3-TI only, is presented. The annealing of Sb2Te3 markedly improves its crystalline quality, leading to an increased fraction of ferromagnetic Fe atoms at the buried Fe/Sb2Te3 interface and a slight lowering of the Fe layer coercive field. This is quite surprising, since the bi-layer is not subjected to any thermal treatment upon Fe deposition. This method is an efficient tool to clean-up the Fe/Sb2Te3 interface, which may be extended to different FM/TI heterostructures. Simultaneously to the interface reconstruction, a constant 20% fraction of FeTe develops at the interface. Since ultrathin FeTe has been reported to be superconducting, these results can open perspective in exploiting phenomena at the edge of magnetism, superconductivity and topology.

Ethylene glycol was studied as solvent for the electrodeposition of iron from both bivalent and trivalent iron chloride solutions. Using cyclic voltammetry (CV) on Pt electrodes, the impossibility to directly reduce Fe(III) ions to metallic state Fe(0) was evidenced with the formation of Fe(II) species as intermediate step for iron plating. Linear sweep voltammetries (LSVs) were carried out on copper substrate confirming the results previously obtained on platinum. Potentiostatic depositions were performed from both Fe(II) and Fe(III) solutions in a broad potential interval (from −1.5 to −2.3 V vs Pt) to define the threshold value for iron reduction and film formation: the best results were obtained at −1.7 V vs Pt for Fe(II) solution and at −2.3 V vs Pt for Fe(III) one. Deposits were characterized with field emission scanning electron microscope (FE-SEM) showing a nanostructured morphology with no traces of oxygen in the deposits, resulting in a pure metallic plated iron: films showed a corrosion potential (Ecorr = −0.54 V vs Ag/AgCl ) in 3.5 wt% NaCl aqueous solution similar to high purity metallurgical iron sheet (Ecorr = −0.4 V vs Ag/AgCl ). X-Ray diffraction patterns showed a preferential orientation of the nanocrystalline deposit along the BCC [110] direction. Vibrating sample magnetometer (VSM) analysis showed a good saturation magnetization (1500 ± 100 kA/m) and low coercivity (∼20 Oe) indicative of a high purity iron film.

In this paper, we report on the magnetic and chemical characterization of the exchange-biased CoFeB/IrMn bilayers, grown by magnetron sputtering on a Si-based platform and capped by either a Ru or MgO/Ru overlayer. For Ru capping, the blocking temperature monotonously increases with the IrMn thickness within the investigated range (3.5–8 nm). On the contrary, for MgO/Ru capping, the exchange bias is inhibited below 6 nm, whereas above 6 nm, the magnetic behavior is the same of Ru-capped films. The chemical analysis reveals a significant dependence of the Mn content from the capping layer for thin IrMn films (2.5 nm), whereas the difference disappears when IrMn becomes thick (7 nm). Our work suggests that a non-uniform composition of the IrMn films directly affects the exchange coupling at the IrMn/CoFeB interface.

We report a combined theoretical and experimental investigation of magnetic proximity and Hall transport in Pt/Cr bilayers. Density functional theory indicates that an interfacial magnetization can be induced in the Pt layer and a strong magnetocrystalline anisotropy with an easy axis out of plane arises in the antiferromagnet. A signal ascribed to the anomalous Hall effect is detected and associated to the interface between Pt and Cr layers. We show that this effect originates from the combination of proximity-induced magnetization and a nontrivial topology of the band structure at the interface.

By performing density functional theory and Green's functions calculations, complemented by x-ray photoemission spectroscopy, we investigate the electronic structure of Fe/GeTe(111), a prototypical ferromagnetic/Rashba-ferroelectric interface. We reveal that such a system exhibits several intriguing properties resulting from the complex interplay of exchange interaction, electric polarization, and spin-orbit coupling. Despite a rather strong interfacial hybridization between Fe and GeTe bands, resulting in a complete suppression of the surface states of the latter, the bulk Rashba bands are hardly altered by the ferromagnetic overlayer. This could have a deep impact on spin-dependent phenomena observed at this interface, such as spin-to-charge interconversion, which are likely to involve bulk rather than surface Rashba states.

Converse magnetoelectric coupling in artificial multiferroics is generally modeled through three possible mechanisms: charge transfer, strain mediated effects or ion migration. Here the role played by electrically controlled morphological modifications on the ferromagnetic response of a multiferroic heterostructure, specifically FexMn1-x ferromagnetic films on piezoferroelectric PMN-PT [001] substrates, is discussed. The substrates present, in correspondence to electrical switching, fully reversible morphological changes at the surface, to which correspond reproducible modifications of the ferromagnetic response of the FexMn1-x films. Topographic analysis by atomic force microscopy shows the formation of surface cracks (up to 100 nm in height) upon application of a sufficiently high positive electric field (up to 6 kV cm-1). The cracks disappear after application of negative electric field of the same magnitude. Correspondingly, in operando X-ray magnetic circular dichroic spectroscopy at Fe edge in FexMn1-x layers and micro-MOKE measurements show local variations in the intensity of the dichroic signal and in the magnetic anisotropy as a function of the electrically driven morphological state. This morphologic parameter, rarely explored in literature, directly affects the ferromagnetic response of the system. Its proof of electrically reversible modification of the magnetic response adds a new possibility in the design of electrically controlled magnetic devices.

Interfaces play a crucial role in the study of novel phenomena emerging at heterostructures comprising metals and functional oxides. In this work, we consider Cr/BaTiO3 heterostructures grown on Nb:SrTiO3 (0 0 1) substrates. Chromium thin films with 2 nm nominal thickness are deposited by molecular beam epitaxy on the BaTiO3 layer, and subsequently annealed in vacuum at temperatures ranging from 800 K to 970 K, and finally exposed to 10−7 torr of molecular oxygen for 300 s. Highly ordered films are obtained for each of this condition, ranging from metallic Cr to insulating Cr2O3 with tetragonal structure. Quite unexpectedly, an intermediate – fully ordered – case exists, with the co-presence of Cr and Cr2O3 compounds, each one with its proper crystal orientation. These results show the opportunity of controlling the metal/oxide state of crystalline Cr films grown onto the ferroelectric template BaTiO3/Nb:SrTiO3.

Electrodeposited cobalt nickel phosphorus alloys are characterized by interesting magnetic properties, which motivate their potential applicability in micro-electromagnetic devices like sensors and actuators. CoNiP is suitable for MEMS fabrication due to its relatively high coercivity and maximum magnetic energy product. Moreover, the columnar grain structure typical of electrodeposited layers introduces a high magnetic anisotropy, which is desirable for devices that require high magnetic flux and energy product along a specific direction [1]. In addition to their magnetic properties, CoNiP alloys are also characterized by high hardness, which makes them good candidates for the production of anti-wear coatings, and by good corrosion resistance. Finally, CoNiP coatings show a notable catalytic activity, which can be exploited in water splitting applications [2]. One of the most remarkable advantages of using electrodeposition for CoNiP production is the possibility to easily tune magnetic properties by varying deposition parameters. Physical and chemical parameters like bath composition, temperature, pH, presence of additives have a great role on final properties determination [3]. Magnetic behavior can be soft or semi-hard according to the conditions employed. Magnetic properties, however, depend not only on the chemistry of the electrolyte and the primary plating parameters, but also on other secondary deposition aspects. These include, for example, the substrate on which the alloy is plated [4] and its roughness [5]. Furthermore, the application of an external magnetic field during the deposition can influence final properties of the deposited layer. Finally, also the presence of inert particles codeposited within the CoNiP layer can change the magnetic behavior of the coatings. In this context, CoNiP has been poorly characterized in the existing literature. The aim of the present work is to explore the influence of some secondary deposition parameters on CoNiP magnetic properties. In detail, a CoNiP electrolyte was selected and its chemical composition was kept constant during the experimentation. The same was done with the deposition parameters. CoNiP was deposited on different substrates, characterized by different materials (brass, copper, silver) and by different degrees of roughness. The alloy was also codeposited with inert (TiO2) nanoparticles and in presence of an external magnetic field. The influence of these variables on final magnetic properties was investigated with vibrating sample magnetometry (VSM). Surface morphology and phase composition were characterized by mean of SEM and XRD. CoNiP layers were also annealed, and the effect of the heat treatment on magnetic properties was studied. Finally, the observed substrate sensitivity of CoNiP magnetic properties was exploited to introduce a surface magnetic anisotropy in electrodeposited CoNiP layers. Brass substrates were patterned with electrodeposited copper and CoNiP was deposited on top. Magnetic force microscopy (MFM) was employed to characterize the result, evidencing differences in magnetic properties between the zones where CoNiP was plated on brass and the zones where CoNiP was plated on electrodeposited copper. The final result was a magnetically patterned CoNiP coating, which may potentially find application in microelectronics and sensors production. [1] C. J. Hsiao et al., AIP Advances 7, 056210 (2017) [2] A. Han et al., J. Mater. Chem. A 4, 10195 (2016) [3] P. Cojocaru et al., Trans. Inst. Met. Fin. 89(4), 194 (2011) [4] E. I. Manimaran et al., J. Mater. Sci. Mater. Electron. 26, 9821 (2015) [5] S. J. Steinmuller et al., J. Appl. Phys. 101, 09D113 (2007)

Integrated optically inspired wave-based processing is envisioned to outperform digital architectures in specific tasks, such as image processing and speech recognition. In this view, spin waves represent a promising route due to their nanoscale wavelength in the gigahertz frequency range and rich phenomenology. Here, a versatile, optically inspired platform using spin waves is realized, demonstrating the wavefront engineering, focusing, and robust interference of spin waves with nanoscale wavelength. In particular, magnonic nanoantennas based on tailored spin textures are used for launching spatially shaped coherent wavefronts, diffraction-limited spin-wave beams, and generating robust multi-beam interference patterns, which spatially extend for several times the spin-wave wavelength. Furthermore, it is shown that intriguing features, such as resilience to back reflection, naturally arise from the spin-wave nonreciprocity in synthetic antiferromagnets, preserving the high quality of the interference patterns from spurious counterpropagating modes. This work represents a fundamental step toward the realization of nanoscale optically inspired devices based on spin waves.

According to World Health Organization(WHO), 3.2 billion people are at risk for malaria. In 2015, 212 million new cases and 429000 deaths were estimated [1, 2]. Despite treatment in the early stage of the disease is usually very effective, conventional diagnostic tests via optical microscopy examination of thick and thin blood smears are unsuitable for an effective screening of the population. On the other hand, the over-treatment of the disease due to the large percentage of false positives in currently available rapid diagnostic tests (RDTs) may increase the risk of drug resistance. In this scenario, there is a strong need of novel RTDs with (i) the same sensitivity of the gold standard (optical microscopy examination) and (ii) a reduced number of false positives. To fulfill the last requirement, a real improvement would be to move from the detection of antigens or antibodies, which can be hardly washed out in a patient living in an endemic zone even after many weeks from the last malaria episode, to the quantification of infected red blood cells in a blood smear (i-RBC). This essentially means to go back to the concept of gold standard tests, with the additional requirement of integrating i-RBC counting in lab-on-chip platforms suitable for low-cost, rapid and on-site wide screening of the population in endemic zones. It is well known that i-RBCs display a paramagnetic behavior with respect to blood plasma, so that they can be separated from healthy ones and other corpuscles in a high magnetic field gradient. [3] This is due to the fact that, during the intra-erythrocytic development, the parasite degrades hemoglobin into free heme. This molecule, highly toxic to the parasite, is converted in an insoluble form, known as hemozoin or malaria pigment, which crystallizes into paramagnetic nanocrystals found both within the i-RBCs and free in the blood, after RBCs lysis. Of course, both the concentration of free hemozoin crystals and i-RBCs can be used for the determination of the parasitemia. In this paper we present an on-chip magnetophoretic platform for the separation and concentration of i-RBC and hemozoin nanocrystals on pre-defined areas of a chip. This is a pre-requisite for the quantification of the relative percentage of i-RBC with respect to healthy ones (parasitemia) with high sensitivity. The blood drop is placed on a glass substrate, which is then put in close contact to the surface of a chip with Nickel micropillars, at a distance defined by an outer ring which defines also the volume of the cell where magnetophoretic separation takes place. The chip is placed face-down, so that magnetic attraction towards the nickel pillars, in the macroscopic field gradient produced by an external system of permanent magnets, opposes the gravity. In this configuration, i-RBCs and hemozoin crystals are attracted upwards, towards the micropillars, while non-infected erythrocytes and the other blood cells (i.e. white blood cells and platelets) sediment towards the glass substrate. Our design allows to obtain a macroscopic field gradient as high as $1\times 10 ^{15}$ A2/m3 up to a distance of 500 micron from the chip surface, strong enough to overcome gravity and attract i-RBCs and hemozoin crystals towards the chip surface. The chip consists of an array of Ni pillars, with 20–30 micron diameter and 20 micron height, fabricated by electroplating and arranged on a hexagonal closed packed lattice. In close proximity to the chip surface, Ni pillars produce a much stronger field gradient, up to $3\times 10 ^{16}$ A2/m3 at a few microns from their surface, which concentrate the i-RBCs and hemozoin crystals. We have tested this system using RBCs from bovine blood, treated with NaNO 2 in order to induce the transformation of hemoglobin into paramagnetic meta-hemoglobin. [4] In this way, we obtained suspensions in PBS of RBCs mimicking i-RBCs, suitable for experiments of capture. In figure 1 we report optical images from experiments performed in a direct configuration, where gravity and magnetic forces act in the same direction. Untreated RBCs (ut-RBCs) and treated ones with NaNO2 (t-RBCs) were stained with a red fluorophore to improve the quality of optical images. As evident from Figure 1, in case of t-RBCs we observed a capture efficiency of 100% by magnetic pillars in a lattice with center to center spacing of 80 microns. For hemozoin crystals the capture is even easier, because of their much larger volume susceptibility, $3.4\times 10 ^{-4}$ to be compared with $3.9\times 10 ^{-6}$ in case of i-RBCs. These results pave the way to the use of our magnetic chips as active slides for the magnetophoretic separation and concentration of malaria markers, both i-RBCs and hemozoin crystals, in well-defined areas of the chips where quantification can be performed with high sensitivity.

Domain switching in polycrystalline BaTiO3 is exploited to realize self-holding phase actuators in Si-photonics. A non-volatile change of the BaTiO3 refractive-index is achieved and poly-BaTiO3-coated silicon photonic circuits are demonstrated.

The electric and nonvolatile control of the spin texture in semiconductors would represent a fundamental step toward novel electronic devices combining memory and computing functionalities. Recently, GeTe has been theoretically proposed as the father compound of a new class of materials, namely ferroelectric Rashba semiconductors. They display bulk bands with giant Rashba-like splitting due to the inversion symmetry breaking arising from the ferroelectric polarization, thus allowing for the ferroelectric control of the spin. Here, we provide the experimental demonstration of the correlation between ferroelectricity and spin texture. A surface-engineering strategy is used to set two opposite predefined uniform ferroelectric polarizations, inward and outward, as monitored by piezoresponse force microscopy. Spin and angular resolved photoemission experiments show that these GeTe(111) surfaces display opposite sense of circulation of spin in bulk Rashba bands. Furthermore, we demonstrate the crafting of nonvolatile ferroelectric patterns in GeTe films at the nanoscale by using the conductive tip of an atomic force microscope. Based on the intimate link between ferroelectric polarization and spin in GeTe, ferroelectric patterning paves the way to the investigation of devices with engineered spin configurations.

Interfaces play a crucial role in the study of novel phenomena emerging at heterostructures comprising metals and functional oxides. For this reason, attention should be paid to the interface chemistry, which can favor the interdiffusion of atomic species and, under certain conditions, lead to the formation of radically different compounds with respect to the original constituents. In this work, we consider Cr/BaTiO3 heterostructures grown on SrTiO3 (100) substrates. Chromium thin films (1-2 nm thickness) are deposited by molecular beam epitaxy on the BaTiO3 layer, and subsequently annealed in vacuum at temperatures ranging from 473 to 773 K. A disordered metallic layer is detected for annealing temperatures up to 573 K, whereas, at higher temperatures, we observe a progressive oxidation of chromium, which we relate to the thermally activated migration of oxygen from the substrate. The chromium oxidation state is + 3 and the film shows a defective rocksalt structure, which grows lattice matched on the underlying BaTiO3 layer. One out of every three atoms of chromium is missing, producing an uncommon tetragonal phase with Cr2O3 stoichiometry. Despite the structural difference with respect to the ordinary corundum alpha-Cr2O3 phase, we demonstrate both experimentally and theoretically that the electronic properties of the two phases are, to a large extent, equivalent.

Spin-orbit coupling effects in materials with broken inversion symmetry are responsible for peculiar spin textures. Among them, ferroelectric materials allow for non-volatile control of the spin degree of freedom through the non-volatile electrical inversion of the spin texture, through to their reversible spontaneous polarization. Such functionality holds potential for technological applications exploiting spin effects controlled by electric fields. The ferroelectric Rashba semiconductor Germanium Telluride stands out as material for Spin-Orbitronics: its ferroelectricity provides a nonvolatile state variable able to generate and drive a giant bulk Rashba-type spin splitting of the electronic bands, while its semiconductivity would allow for the realization of spin-based transistors. The ferroelectric control of the bands topology and of the spin texture is expected to reflect in the tunability of the spin transport properties. Here we exploit the unidirectional spin Hall magnetoresistance of Fe/GeTe heterostructures to characterize charge-to-spin conversion in GeTe. Our preliminary results indicate a sizable conversion efficiency at low temperature (120 K), which promotes ferroelectric Rashba semiconductors as promising candidates for the implementation of non-volatile electrically reconfigurable computing devices based on spin transport in semiconductors.

Tetragonal phase of CuMnAs progressively appears as one of the key materials for antiferromagnetic spintronics due to efficient current-induced spin-orbit torques whose existence can be directly inferred from crystal symmetry. Theoretical understanding of spintronic phenomena in this material, however, relies on the detailed knowledge of electronic structure (band structure and corresponding wave functions) which has so far been tested only to a limited extent. We show that AC permittivity (obtained from ellipsometry) and UV photoelectron spectra agree with density functional calculations. Together with the x-ray diffraction and precession electron diffraction tomography, our analysis confirms recent theoretical claim [Phys.Rev.B 96, 094406 (2017)] that copper atoms occupy lattice positions in the basal plane of the tetragonal unit cell., 5 pages, 5 figures + Supplementary Information

The introduction of multigene panel testing for hereditary breast/ovarian cancer screening has greatly improved efficiency, speed, and costs. However, its clinical utility is still debated, mostly due to the lack of conclusive evidences on the impact of newly discovered genetic variants on cancer risk and lack of evidence‐based guidelines for the clinical management of their carriers. In this pilot study, we aimed to test whether a systematic and multiparametric characterization of newly discovered mutations could enhance the clinical utility of multigene panel sequencing. Out of a pool of 367 breast/ovarian cancer families Sanger‐sequenced for BRCA1 and BRCA2 gene mutations, we selected a cohort of 20 BRCA1/2‐negative families to be subjected to the BROCA‐Cancer Risk Panel massive parallel sequencing. As a strategy for the systematic characterization of newly discovered genetic variants, we collected blood and cancer tissue samples and established lymphoblastoid cell lines from all available individuals in these families, to perform segregation analysis, loss‐of‐heterozygosity and further molecular studies. We identified loss‐of‐function mutations in 6 out 20 high‐risk families, 5 of which occurred on BRCA1,CHEK2 and ATM and are esteemed to be risk‐relevant. In contrast, a novel RAD50 truncating mutation is most likely unrelated to breast cancer. Our data suggest that integrating multigene panel testing with a pre‐organized, multiparametric characterization of newly discovered genetic variants improves the identification of risk‐relevant alleles impacting on the clinical management of their carriers.

GeTe has been predicted to be the father compound of a new class of multifunctional materials, ferroelectric Rashba semiconductors, displaying a coupling between spin-dependent k-splitting and ferroelectricity. In this paper, we report on epitaxial Fe/GeTe(111) heterostructures grown by molecular beam epitaxy. Spin-pumping experiments have been performed in a radio-frequency cavity by pumping a spin current from the Fe layer into GeTe at the Fe ferromagnetic resonance and detecting the transverse charge current originated in the slab due to spin-to-charge conversion. Preliminary experiments indicate that a clear spin to charge conversion exists, thus unveiling the potential of GeTe for spin-orbitronics.

Photoelectron spectroscopy in combination with piezoforce microscopy reveals that the helicity of Rashba bands is coupled to the nonvolatile ferroelectric polarization of GeTe(111). A novel surface Rashba band is found and fingerprints of a bulk Rashba band are identified by comparison with density functional theory calculations.

HMGA1 is a member of a small family of architectural transcription factors involved in the coordinate assembly of multiprotein complexes referred to as enhanceosomes. In addition to their role in cell proliferation, differentiation, and development, high-mobility group proteins of the A type (HMGA) family members behave as transforming protoncogenes either in vitro or in animal models. Recent reports indicated that HMGA1 might counteract p53 pathway and provided an interesting hint on the mechanisms determining HMGA's transforming potential. HMGA1 expression is deregulated in a very large array of human tumors, including cervical cancer, but very limited information is available on the molecular mechanisms leading to HMGA1 deregulation in cancer cells. Here, we report that HMGA1 expression is sustained by human papilloma virus (HPV) E6/E7 proteins in cervical cancer, as demonstrated by either E6/E7 overexpression or by repression through RNA interference. Knocking down HMGA1 expression by means of RNA interference, we also showed that it is involved in cell proliferation and contributes to p53 inactivation in this type of neoplasia. Finally, we show that HMGA1 is necessary for the full expression of HPV18 E6 and E7 oncoproteins thus establishing a positive autoregulatory loop between HPV E6/E7 and HMGA1 expression. Copyright © 2008 Neoplasia Press, Inc. All rights reserved.

Germline point mutations in BRCA1 and BRCA2 genes account for about 30% of the inherited breast and ovarian cancers. Germline genomic rearrangements have been found in both BRCA1 and BRCA2 genes, but the extent to which these alterations might contribute to increasing the actual mutation detection rate is still debated. Here we screened a cohort of 112 consecutive Italian families at moderate-to-high risk for breast and/or ovarian cancer for BRCA1 and BRCA2 point mutations and genomic rearrangements. Of the 83 point mutation negative probands, two (2.4%) showed BRCA1 rearrangements, accounting for 10.5% of the BRCA1 mutations. BRCA1 del18-19 has been previously described in another Italian family, while the molecular characterization of the BRCA1 del23-24 is given here for the first time. Conversely, we failed to identify any BRCA2 rearrangements even in the hereditary breast cancer families, where we detected an higher prevalence of BRCA2 compared to BRCA1 point mutations. Our results support the idea that search for BRCA1 rearrangements should be included in the genetic screening of even moderate risk breast/ovarian cancer families. In contrast, they suggest BRCA2 rearrangements might be very rare out of the high risk families including a male breast cancer.

High mobility group A1 (HMGA1) is an architectural transcription factor and a putative protoncogene. Deregulation of its expression has been shown in most human cancers. We have previously shown that the expression of the HMGA family members is deregulated in neuroblastoma cell lines and primary tumors. On retinoic acid (RA) treatment of MYCN-amplified neuroblastoma cell lines, HMGA1 decreases with a kinetics that strictly follows MYCN repression. In addition, MYCN constitutive expression abolishes HMGA1 repression by RA. Here we explored the possibility that HMGA1 expression might be sustained by MYCN in amplified cells. Indeed, MYCN transfection induced HMGA1 expression in several neuroblastoma cell lines. HMGA1 expression increased in a transgene dose–dependent fashion in neuroblastoma-like tumors of MYCN transgenic mice. In addition, it was significantly more expressed in MYCN-amplified compared with MYCN single-copy primary human neuroblastomas. MYCN cotransfection activated a promoter/luciferase reporter containing a 1,600 bp region surrounding the first three transcription start sites of the human HMGA1 and eight imperfect E-boxes. By heterodimerizing with its partner MAX, MYCN could bind to multiple DNA fragments within the 1,600 bp. Either 5′ or 3′ deletion variants of the 1,600 bp promoter/luciferase reporter strongly decreased luciferase activity, suggesting that, more than a single site, the cooperative function of multiple cis-acting elements mediates direct HMGA1 transactivation by MYCN. Finally, HMGA1 repression by RNA interference reduced neuroblastoma cell proliferation, indicating that HMGA1 is a novel MYCN target gene relevant for neuroblastoma tumorigenesis.

Frequent mutations of coding nucleotide repeats are thought to contribute significantly to carcinogenesis associated with microsatellite instability (MSI). We have shown that shortening of the poly(T)11 within the polypyrimidine stretch/accessory splicing signal of human MRE11 leads to the reduced expression and functional impairment of the MRE11/NBS1/RAD50 complex. This mutation was selectively found in mismatch repair (MMR) defective cell lines and potentially identifies MRE11 as a novel target for MSI. Here, we examined 70 microsatellite unstable primary human cancers and we report that MRE11 mutations occur in 83.7 and 50% of the colorectal and endometrial cancers, respectively. In the colorectal cancer series, mutated MRE11 is more frequently associated with advanced age at diagnosis and A/B stages. Biallelic mutations were present in 38.8% of the cases and more frequently associated with lower (G1/G2) grade tumors. Impaired MRE11 expression was prevalent in primary colorectal tumors with larger and biallelic shortening of the poly(T)11. Immunohistochemistry confirmed the impaired MRE11 expression and revealed NBS1-defective expression in MRE11 mutated cancers. Together with the observation that perturbation of the MRE11/NBS1/RAD50 complex predisposes to cancer, our work highlights MRE11 as a new common target in the MMR deficient tumorigenesis and suggests its role in colorectal carcinogenesis.

Ge-based spin-photodiodes have been employed to investigate the spectral dependence of optical spin orientation in germanium, in the range 400--1550 nm. We found the expected maximum in the spin polarization of photocarriers for excitation at the direct gap in $\ensuremath{\Gamma}$ (1550 nm) and a second sizable peak due to photogeneration in the $L$ valleys (530 nm). Data suggest distinct spin depolarization mechanisms for excitation at $\ensuremath{\Gamma}$ and $L$, with shorter spin relaxation times whether the $X$ point is involved. These devices can be used as integrated photon-helicity detectors over a wide spectral range.

Recent studies have demonstrated the potential of antiferromagnets as the active component in spintronic devices. This is in contrast to their current passive role as pinning layers in hard disk read heads and magnetic memories. Here we report the epitaxial growth of a new high-temperature antiferromagnetic material, tetragonal CuMnAs, which exhibits excellent crystal quality, chemical order and compatibility with existing semiconductor technologies. We demonstrate its growth on the III-V semiconductors GaAs and GaP, and show that the structure is also lattice matched to Si. Neutron diffraction shows collinear antiferromagnetic order with a high Ne\'el temperature. Combined with our demonstration of room-temperature exchange coupling in a CuMnAs/Fe bilayer, we conclude that tetragonal CuMnAs films are suitable candidate materials for antiferromagnetic spintronics., Comment: 16 pages, 5 figures, Published in Nature Communications (2013)