We report the measurement of a spin pumping effect due to fluctuations of the magnetic order of IrMn thin films. A precessing NiFe ferromagnet injected spins into IrMn spin sinks, and enhanced ...damping was observed around the IrMn magnetic phase transition. Our data were compared to a recently developed theory and converted into interfacial spin mixing conductance enhancements. By spotting the spin pumping peak, the thickness dependence of the IrMn critical temperature could be determined and the characteristic length for the spin-spin interactions was deduced.
The Rashba effect is an interaction between the spin and the momentum of electrons induced by the spin-orbit coupling (SOC) in surface or interface states. Its potential for conversion between charge ...and spin currents has been theoretically predicted but never clearly demonstrated for surfaces or interfaces of metals. Here we present experiments evidencing a large spin-charge conversion by the Bi/Ag Rashba interface. We use spin pumping to inject a spin current from a NiFe layer into a Bi/Ag bilayer and we detect the resulting charge current. As the charge signal is much smaller (negligible) with only Bi (only Ag), the spin-to-charge conversion can be unambiguously ascribed to the Rashba coupling at the Bi/Ag interface. This result demonstrates that the Rashba effect at interfaces can be used for efficient charge-spin conversion in spintronics.
Through combined ferromagnetic resonance, spin pumping, and inverse spin Hall effect experiments in Co|Pt bilayers and Co|Cu|Pt trilayers, we demonstrate consistent values of ℓsfPt=3.4±0.4 nm and ...θSHEPt=0.056±0.010 for the respective spin diffusion length and spin Hall angle for Pt. Our data and model emphasize the partial depolarization of the spin current at each interface due to spin-memory loss. Our model reconciles the previously published spin Hall angle values and explains the different scaling lengths for the ferromagnetic damping and the spin Hall effect induced voltage.
The capacity to propagate magnetic domain walls with spin-polarized currents underpins several schemes for information storage and processing using spintronic devices. A key question involves the ...internal structure of the domain walls, which governs their response to certain current-driven torques such as the spin Hall effect. Here we show that magnetic microscopy based on a single nitrogen-vacancy defect in diamond can provide a direct determination of the internal wall structure in ultrathin ferromagnetic films under ambient conditions. We find pure Bloch walls in Ta/CoFeB(1 nm)/MgO, while left-handed Néel walls are observed in Pt/Co(0.6 nm)/AlOx. The latter indicates the presence of a sizable interfacial Dzyaloshinskii-Moriya interaction, which has strong bearing on the feasibility of exploiting novel chiral states such as skyrmions for information technologies.
The spin-orbit interaction couples the electrons' motion to their spin. As a result, a charge current running through a material with strong spin-orbit coupling generates a transverse spin current ...(spin Hall effect, SHE) and vice versa (inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronic functionalities and devices, some of which do not require any ferromagnetic material. However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronic hetero- and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism-the Rashba effect-in the oxide two-dimensional electron system (2DES) LaAlO
/SrTiO
to achieve spin-to-charge conversion with unprecedented efficiency. Through spin pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES and highlight the importance of a long scattering time to achieve efficient spin-to-charge interconversion.
A new approach to increase the downsize scalability of perpendicular STT-MRAM is presented. It consists of significantly increasing the thickness of the storage layer in out-of-plane magnetized ...tunnel junctions (pMTJ) as compared to conventional pMTJ in order to induce a perpendicular shape anisotropy (PSA) in this layer. This PSA is obtained by depositing a thick ferromagnetic (FM) layer on top of an MgO/FeCoB based magnetic tunnel junction (MTJ) so that the thickness of the storage layer is of the order of or larger than the diameter of the MTJ pillar. In contrast to conventional spin transfer torque magnetic random access memory (STT-MRAM) wherein the demagnetizing energy opposes the interfacial perpendicular magnetic anisotropy (iPMA), in these novel memory cells, both PSA and iPMA contributions favor the out-of-plane orientation of the storage layer magnetization. Using thicker storage layers in these PSA-STT-MRAMs has several advantages. Due to the PSA, very high and easily tunable thermal stability factors can be achieved, even down to sub-10 nm diameters. Moreover, a low damping material can be used for the thick FM material thus leading to a reduction of the write current. The paper describes this new PSA-STT-MRAM concept, practical realization of such memory arrays, magnetic characterization demonstrating thermal stability factor above 200 for MTJs as small as 8 nm in diameter and possibility to maintain the thermal stability factor above 60 down to 4 nm diameter.
A new approach to increase the downsize scalability of perpendicular STT-MRAM is presented.
A new spin for oxide interfaces Varignon, J.; Vila, L.; Barthélémy, A. ...
Nature physics,
04/2018, Letnik:
14, Številka:
4
Journal Article
Recenzirano
The variety of emergent phenomena occurring at oxide interfaces has made these systems the focus of intense study in recent years. We argue that spin–orbit effects in oxide interfaces provide a ...versatile handle to generate, control and convert spin currents, with a view towards low-power spintronics.
We present measurements of pure spin current absorption on lateral spin valves. By varying the width of the absorber we demonstrate that spin current absorption measurements enable one to ...characterize efficiently the spin transport properties of ferromagnetic elements. The analytical model used to describe the measurement takes into account the polarization of the absorber. The analysis of the measurements thus allows the determination of the polarization and the spin diffusion length of a studied material independently, contrary to most experiments based on lateral spin valves where those values are entangled. We report the spin transport parameters of some of the most important materials used in spinorbitronics (Co60Fe40, Ni81Fe19, Co, Pt, and Ta), at room and low (10 K) temperatures.
Objective: We sought to determine the effect of hydroxychloroquine therapy on the levels proinflammatory/prothrombotic markers and disease activity scores in patients with systemic lupus ...erythematosus (SLE) in a multiethnic, multi-center cohort (LUMINA). Methods: Plasma/serum samples from SLE patients (n = 35) were evaluated at baseline and after hydroxychloroquine treatment. Disease activity was assessed using SLAM-R scores. Interferon (IFN)-α2, interleukin (IL)-1β, IL-6, IL-8, inducible protein (IP)-10, monocyte chemotactic protein-1, tumor necrosis factor (TNF)-α and soluble CD40 ligand (sCD40L) levels were determined by a multiplex immunoassay. Anticardiolipin antibodies were evaluated using ELISA assays. Thirty-two frequency-matched plasma/serum samples from healthy donors were used as controls. Results: Levels of IL-6, IP-10, sCD40L, IFN-α and TNF-α were significantly elevated in SLE patients versus controls. There was a positive but moderate correlation between SLAM-R scores at baseline and levels of IFN-α (p = 0.0546). Hydroxychloroquine therapy resulted in a significant decrease in SLAM-R scores (p = 0.0157), and the decrease in SLAM-R after hydroxychloroquine therapy strongly correlated with decreases in IFN-α (p = 0.0087). Conclusions: Hydroxychloroquine therapy resulted in significant clinical improvement in SLE patients, which strongly correlated with reductions in IFN-α levels. This indicates an important role for the inhibition of endogenous TLR activation in the action of hydroxychloroquine in SLE and provides additional evidence for the importance of type I interferons in the pathogenesis of SLE. This study underscores the use of hydroxychloroquine in the treatment of SLE.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Acute food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated condition involving gastrointestinal hypersensitivity to food that is characterized by profuse vomiting 1-4 hours after ...ingestion. It may be accompanied by pallor, lethargy, hypotension, and hypothermia. Although classically considered a pediatric disorder, several reports in adults have been published since 2012. Our aim was to describe the clinical features of acute FPIES in Spanish adults by comparing our findings with those previously published on adult and pediatric populations. We performed a retrospective chart review of patients referred to our outpatient allergy unit from 2017 to 2020 because of clinical manifestations compatible with FPIES. Patients underwent skin prick tests (SPTs) with commercial extracts (ALK Abelló) and prick-by-prick tests with fresh food and total and specific IgE (ImmunoCAP, Thermo Fisher).
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