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We report the electrical detection of the antiferromagnetic state of IrMn through anomalous Hall measurements in Ta/IrMn heterostructures. The magnetic state is set in the antiferromagnet through field cooling and detected electrically by transverse resistance measurements in Hall bar structures without the need for any ferromagnetic layer. The amplitude of the signal increases with the magnetic field applied during the cooling and is enhanced by the proximal interface with a Ta layer. From the temperature dependence of the effect and the comparison between Ta/IrMn and Ru/IrMn interfaces, we propose an explanation of such readouts based on the simultaneous occurrence of spin-Hall magnetoresistance and magnetic proximity in Ta. These findings highlight how interface effects could be generally employed for the investigation of antiferromagnetic materials as well as for the electrical readout of the antiferromagnetic state. [ABSTRACT FROM AUTHOR]

In-vitro tests and analyses are of fundamental importance for investigating biological mechanisms in cells and bio-molecules. The controlled application of forces to activate specific bio-pathways and investigate their effects, mimicking the role of the cellular environment, is becoming a prominent approach in this field. In this work, we present a non-invasive magnetic on-chip platform which allows for the manipulation of magnetic particles, through micrometric magnetic conduits of Permalloy patterned on-chip. We show, from simulations and experiments, that this technology permits to exert a finely controlled force on magnetic beads along the chip surface. This force can be tuned from few to hundreds pN by applying a variable external magnetic field. [ABSTRACT FROM AUTHOR]

Interfacial MagnetoElectric coupling (MEC) at ferroelectric/ferromagnetic interfaces has recently emerged as a promising route to achieve electrical writing of magnetic information in spintronic devices. For the prototypical Fe/BaTiO3 (BTO) system, various MEC mechanisms have been theoretically predicted. Experimentally, it is well established that using BTO single crystal substrates MEC is dominated by strain-mediated mechanisms. In case of ferromagnetic layers epitaxially grown onto BTO films, instead, no direct evidence for MEC has been provided, apart from the results obtained on tunneling junction sandwiching a BTO tunneling barrier. In this paper, MEC at fully epitaxial Fe/BTO interface is investigated by Magneto-Optical Kerr Effect and magnetoresistance measurements on magnetic tunnel junctions fabricated on BTO. We find no evidence for strain-mediated MEC mechanisms in epitaxial systems, likely due to clamping of BTO to the substrate. Our results indicate that pure electronic MEC is the route of choice to be explored for achieving the electrical writing of information in epitaxial ferromagnet-ferroelectric heterostructures. [ABSTRACT FROM AUTHOR]

We report on the growth of epitaxial Fe/MgO/Ge(001) heterostructures by molecular beam epitaxy. The lowest oxidation and highest sharpness of the MgO/Ge interface, corresponding to a transition layer on the order of one Ge unit cell, is obtained for room temperature growth of the MgO layer followed by annealing in a vacuum at 500 °C. In these conditions, the MgO layer grows epitaxially on Ge(001) with the [110] direction parallel to the [100] direction of Ge, at variance with the cube-on-cube growth on Si(001) and GaAs(001). However, in some cases, the cube-on-cube growth mode of MgO on Ge competes with the mode involving a 45° rotation, as revealed by transmission electron microscopy and photoelectron diffraction data on MgO films grown at 300 °C without postannealing, and on p-doped Ge substrates. For the Fe overlayer, in all the cases reported, room temperature growth followed by annealing up to 200 °C gives rise to a sharp interface and the well-known 45° rotation of the Fe lattice with respect to the MgO lattice. [ABSTRACT FROM AUTHOR]

The control of the magnetization in ferromagnetic layers via electric fields is a hot topic in view of applications to the next generation of spintronic devices, where writing the magnetic information through current lines could be replaced by electric writing. Mixed valence manganites are good candidates for such a purpose because they present an intriguing coupling between ferromagnetism and charge ordering/doping which can be tuned by the application of an electric field. Here we present results on the near-room temperature control of the magnetization of optimally doped La0.67Sr0.33MnO3 ultrathin films in vertical field effect devices, where they act as top or bottom electrodes. In the latter case a slight decrease in the Curie temperature (∼5 K) is observed after application of 5×107 V/m, i.e., the maximum field preventing electric breakdown, compatible with the induced variation in the charge density and mixed valence within the Thomas Fermi screening length. These results indicate that electric fields achievable in vertical field effect devices, of the same entity of interfacial fields originating from differences in the work function in heterostructures, have only minor influence on the magnetic properties of optimally doped ultrathin La0.67Sr0.33MnO3 films. [ABSTRACT FROM AUTHOR]

We report an x-ray photoemission spectroscopy study of the Au/La0.67Sr0.33MnO3 interface formation, aiming to investigate interface abruptness and possible chemical interdiffusion. Our results indicate that the gold deposition does not affect the chemical properties of manganite film and no interdiffusion or segregation takes place. [ABSTRACT FROM AUTHOR]

Hemozoin crystals, also known as malaria pigment, are the by-products of hemoglobin degradation by the Plasmodium parasite during its intra-erythrocytic development. Although it is well known that they are responsible for the peculiar paramagnetic behavior of infected red blood cells, their physical properties are not well known. Here, we show that synthetic hemozoin nanocrystals display an insulating and paramagnetic behavior. Conductive atomic force microscopy measurements on crystals dispensed over flat Au films revealed that hemozoin crystals are insulating, with a breakdown field larger than 5 × 107 V m−1. The magnetic susceptibility, measured with a vibrating sample magnetometer, is 4.1 ± 0.6 × 10−4, compatible with a paramagnetic behavior. These results are confirmed by impedimetric and magnetophoretic measurements on aqueous suspensions of hemozoin crystals. [ABSTRACT FROM AUTHOR]

In vivo, cells are frequently exposed to multiple mechanical stimuli arising from the extracellular microenvironment, with a deep impact on many biological functions. On the other hand, current methods for mechanobiology do not allow one to easily replicate in vitro the complex spatio-temporal profile of such mechanical signals. Here we introduce a new platform for studying the mechanical coupling between single cells and a dynamic extracellular environment, based on active substrates for cell culture made of Fe-coated polymeric micropillars. Under the action of quasi-static external magnetic fields, each group of pillars produces synchronous mechanical stimuli at different points of the cell membrane, thanks to the highly controllable pillars' deflection. This method allows one to apply complex stress fields, resulting in the parallel application of localized forces with tunable intensity and temporal profile. The platform has been validated by studying the cellular response to periodic stimuli in NIH3T3 fibroblasts. We find that low-frequency mechanical stimulation affects the actin cytoskeleton, nuclear morphology, and H2B core-histone dynamics and induces MKL transcription-cofactor translocation from nucleus to cytoplasm. The unique capability of the proposed platform to apply stimuli with a tunable temporal profile and high parallelism on a cell culture holds great potential for the investigation of mechanotransduction mechanisms in cells and tissues. [ABSTRACT FROM AUTHOR]

A promising strategy to get deeper insight on brain functionalities relies on the investigation of neural activities at the cellular and sub-cellular level. In this framework, methods for recording neuron electrical activity have gained interest over the years. Main technological challenges are associated to finding highly sensitive detection schemes, providing considerable spatial and temporal resolution. Moreover, the possibility to perform non-invasive assays would constitute a noteworthy benefit. In this work, we present a magnetoresistive platform for the detection of the action potential propagation in neural cells. Such platform allows, in perspective, the in vitro recording of neural signals arising from single neurons, neural networks and brain slices. [ABSTRACT FROM AUTHOR]

Magnonics is envisioned to enable highly efficient data transport and processing, by exploiting propagating perturbations in the spin-texture of magnetic materials. Despite the demonstrations of a plethora of proof-of-principle devices, the efficient excitation, transport and manipulation of spin-waves at the nanoscale is still an open challenge. Recently, we demonstrated that the spin-wave excitation and propagation can be controlled by nanopatterning reconfigurable spin-textures in a continuous exchange biased ferromagnetic film. Here, we show that by patterning 90° stripe-shaped magnetic domains, we spatially modulate the spin-wave excitation in a continuous film, and that by applying an external magnetic field we can reversibly "switch-off" the spin-wave excitation. This opens the way to the use of nanopatterned spin-textures, such as domains and domain walls, for exciting and manipulating magnons in reconfigurable nanocircuits. [ABSTRACT FROM AUTHOR]

In vitro tests are of fundamental importance for investigating cell mechanisms in response to mechanical stimuli or the impact of the genotype on cell mechanical properties. In particular, the application of controlled forces to activate specific bio-pathways and investigate their effects, mimicking the role of the cellular environment, is becoming a prominent approach in the emerging field of mechanobiology. Here, we present an on-chip device based on magnetic domain wall manipulators, which allows the application of finely controlled and localized forces on target living cells. In particular, we demonstrate the application of a magnetic force in the order of hundreds of pN on the membrane of HeLa cells cultured on-chip, via manipulation of 1 μm superparamagnetic beads. Such a mechanical stimulus produces a sizable local indentation of the cellular membrane of about 2 μm. Upon evaluation of the beads’ position within the magnetic field originated by the domain wall, the force applied during the experiments is accurately quantified via micromagnetic simulations. The obtained value is in good agreement with that calculated by the application of an elastic model to the cellular membrane. [ABSTRACT FROM AUTHOR]

Modular high-temperature gas-cooled reactors (MHTGRs) offer a high degree of passive safety. The low power density of the reactor and the high heat capacity of the graphite core result in slow transients that do not challenge the integrity of the robust TRISO fuel. Another benefit of this fuel form and the surrounding graphite is their superior ability to retain fission products under all anticipated normal and off-normal conditions, which limits reactor accident source terms to very low values. In this paper, we develop estimates of the source term for a generic MHTGR to illustrate the performance of the radionuclide barriers that comprise the MHTGR functional containment. We also examine the influence of initial fuel quality, fuel performance/failure, reactor outlet temperature, and retention outside of the reactor core on the resultant source term to the environment. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate that in Ta/MgO/IrMn tunneling junctions, containing no ferromagnetic elements, distinct metastable resistance states can be set by field cooling the devices from above the Néel temperature (TN) along different orientations. Variations of the resistance up to 10% are found upon field cooling in applied fields, in-plane or out-of-plane. Well below TN, these metastable states are insensitive to magnetic fields up to 2 T, thus constituting robust memory states. Our work provides the demonstration of an electrically readable magnetic memory device, which contains no ferromagnetic elements and stores the information in an antiferromagnetic active layer. [ABSTRACT FROM AUTHOR]

Methods We analyzed the influence of conjugated equine estrogen (CEE) and raloxifene on arterial stiffness. Sixty-seven healthy, normotensive women 1-10 years into menopause were assigned to receive oral placebo, conjugated equine estrogen 0.625 mg, or raloxifene 60 mg. Arterial stiffness was evaluated by measuring the carotid-femoral and femoral-dorsalis pedis pulse wave velocity (CF PWV, FP PWV). Systolic pressure augmentation index (AI) at the carotid artery was obtained with applanation tonometry. Results Arterial stiffness was not affected by any treatment regimen: placebo (CF PWV before vs. after: 644 vs. 626 cm/s, p = 0.09; FP PWV before vs. after: 1006 vs. 1012 cm/s,p = 0.77; AI before vs. after = 30 vs. 29%, p = 0.55), CEE (CF PWV before vs. after: 642 vs. 600 cm/s, p = 0.11; FP PWV before vs. after: 952 vs. 971 cm/s, p = 0.66; AI before vs. after: 25 vs. 32%, p = 0.82), and raloxifene (CF PWV before vs. after: 636 vs. 601 cm/s, p = 0.12; FP PWV before vs. after: 964 vs. 941 cm/s, p = 0.62; AI before vs. after: 25 vs. 25%, p = 0.65). A correlation occurred between basal stiffness and the degree of reduction in indexes measured, indicating that the higher the basal stiffness, the greater the degree of reduction, particularly in the CEE group: CF PWV (r = - 0.602, p = 0.001); FP PWV (r = - 0.455, p = 0.022); AI (r = - 0.410, p = 0.042). Conclusions Conjugated equine estrogen and raloxifene do not seem to affect arterial stiffness of healthy normotensive women less than 10 years since menopause. Reduction in arterial stiffness seems related to its basal level. [ABSTRACT FROM AUTHOR]

This paper will summarize highlights of the safety approach and discuss the ITER EDA safety activities. The ITER safety approach is driven by three major objectives: (1) Enhancement or improvement of fusion's intrinsic safety characteristics to the maximum extent feasible, which includes a minimization of the dependence on dedicated “safety systems”; (2) Selection of conservative design parameters and development of a robust design to accommodate uncertainties in plasma physics as well as the lack of operational experience and data; and (3) Integration of engineered mitigation systems to enhance the safety assurance against potentially hazardous inventories in the device by deploying well-established “nuclear safety” approaches and methodologies tailored as appropriate for ITER. [ABSTRACT FROM AUTHOR]

A number of postulated in-vessel loss of coolant accidents (LOCAs) associated with the first wall and baffle cooling systems of the ITER detailed design have been analyzed for the ITER Non-site Specific Safety Report (NSSR-1). A range of break sizes from one first wall tube break (1.57 × 10−4 m2) to damage to all in-vessel components (0.6 m2 break) have been examined. These events span the ITER event classification from likely events to extremely unlikely events. In addition, in-vessel pipe breaks in combination with bypass of the two confinement barriers through a generic penetration have been examined. In all cases, when the vacuum vessel pressure suppression system is activated, most of the radioactive inventory is carried to the suppression pool where it remains for the duration of the event. Releases in these events are well within ITER release limits. [ABSTRACT FROM AUTHOR]

Accidents involving the ingress of air, helium, or water into the cryostat of the International Thermonuclear Experimental Reactor (ITER) tokamak design have been analyzed with a modified version of the MELCOR code for the ITER Non-site Specific Safety Report (NSSR-1). The air ingress accident is the result of a postulated breach of the cryostat boundary into an adjoining room. MELCOR results for this accident demonstrate that the condensed air mass and increased heat loads are not a magnet safety concern, but that the partial vacuum in the adjoining room must be accommodated in the building design. The water ingress accident is the result of a postulated magnet arc that results in melting of a Primary Heat Transport System (PHTS) coolant pipe, discharging PHTS water and PHTS water activated corrosion products and HTO into the cryostat. MELCOR results for this accident demonstrate that the condensed water mass and increased heat loads are not a magnet safety concern, that the cryostat pressure remains below design limits, and that the corrosion product and HTO releases are well within the ITER release limits. [ABSTRACT FROM AUTHOR]

Magnetoelectric effects in Fe/BaTiO3(001) heterostructures have been investigated via magneto-optical Kerr effect as a function of temperature. We find major modifications of magnetic anisotropies and magnetic coercivity induced by the application of electric fields perpendicular to the interface. Changes in the coercive magnetic field, on the order of 100% at 250 K (in the orthorhombic phase of BaTiO3) and 40% at 300 K (in the tetragonal phase), which are linked to the ferroelectric behavior of BaTiO3, are reported. [ABSTRACT FROM AUTHOR]

We demonstrate the detection of the Brownian relaxation frequency of 250 nm diameter magnetic beads using a lab-on-chip platform based on current lines for exciting the beads with alternating magnetic fields and highly sensitive magnetic tunnel junction (MTJ) sensors with a superparamagnetic free layer. The first harmonic out-of-phase component of the MTJ response gives the imaginary part of the magnetic bead susceptibility, which peaks at the Brownian relaxation frequency. This work paves the way to on-chip implementation of Brownian magnetorelaxometry in innovative 'lab-on-a-bead' assays for biomolecular recognition. [ABSTRACT FROM AUTHOR]

The bandstructure line-up of Fe/MgO/Ge heterostructures with various Ge doping has been determined by x-ray photoemission spectroscopy. The MgO layer causes a sizable depinning of the Fermi level in Ge for light n-(1015 cm-3) and moderate p-doping (1018 cm-3), but not for heavy n-doping (1020 cm-3). The Fermi level instead stays essentially in the middle of the MgO gap for all the investigated doping. This picture agrees with transport measurements only for moderate n- or p-doping, while we demonstrate that for heavy n-doping the analysis of the conductance versus temperature fails in predicting the Schottky barrier height. [ABSTRACT FROM AUTHOR]

Cu2O/La0.7Sr0.3MnO3 is a promising heterostructure for the realization of all-oxide spintronics devices, with La0.7Sr0.3MnO3 (LSMO) and Cu2O playing the roles of ferromagnet and semiconductor, respectively. Here we use x-ray photoelectron spectroscopy and first principles calculations to determine the valence band offset at the Cu2O/LSMO interface. The interface band alignment is typical of a p-type semiconductor/metal contact, with an interface barrier of 0.3–0.5 eV depending on Cu2O thickness. The calculated energetics indicates that the prevailing interface is between SrO-terminated LSMO and Cu planes of Cu2O. [ABSTRACT FROM AUTHOR]

The authors report about La0.67Sr0.33MnO3 single crystal manganite thin films in interaction with a gold capping layer. With respect to uncoated manganite layers of the same thickness, Au-capped 4 nm thick manganite films reveal a dramatic reduction (≃185 K) of the Curie temperature TC and a lower saturation low temperature magnetization M0. A sizable TC reduction (≃60 K) is observed even when an inert SrTiO3 layer is inserted between the gold film and the 4 nm thick manganite layer, suggesting that this effect might have an electrostatic origin. [ABSTRACT FROM AUTHOR]

We report on spin-photodiodes based on fully epitaxial Fe/MgO/Ge(001) heterostructures for the room temperature integrated detection of light helicity at a wavelength of 1300 nm. The degree of circular polarization of light is related to the spin direction of photo-excited carriers in Ge that are filtered by the MgO barrier, with probabilities differing for the two spin channels. Spin-detection experiments are performed by illuminating spin-photodiodes using left or right circularly polarized light under the application of a magnetic field parallel to the light direction and measuring the current crossing the device. We found that the maximum percentage variation of the photocurrent due to full reversal of the light helicity is on the order of 5.9% at room temperature. This variation can be attributed in part to the magnetic circular dichroism of Fe (0.8%) but mainly to the spin filtering of photo-generated carriers across the MgO barrier. [ABSTRACT FROM AUTHOR]