Inter-Layer Coupling Induced Bandgap Reduction in Ultrathin MoS2

We report on a study of highly crystalline islands of MoS2 grown on HOPG substrate. Using STM/STS we find that the valence band edge shifts as a function of the layer number. Numerical calculations reveal the mechanism underlying the bandgap reduction and the role of the interfacial Sulfur atoms is clarified

Attenuation of surface acoustic waves by spin-wave excitations in Co60Fe20B20

The acousto-magnetic attenuation of surface acoustic waves (SAW) in an Co 60 Fe 20 B 20 exchange spring magnet is evidenced experimentally. By high-resolution magnetic imaging using photo-excitation electron microscopy (XPEEM) and magnetometry measurements, the deflection of the ferromagnet from its equilibrium state is visualized. Along a harmonic oscillator model with damping term, the experimental observation of SAW attenuation is attributed to low-frequency spin wave generation in a magnetic exchange spring. Measuring the SAW attenuation at four eigenfrequencies generated via on-chip higher-harmonic generation, we obtain a sub-GHz resonance at f0 = 538 MHz. </jats:p

Imaging of Curved Magnetic Architectures

This is the first book providing overview of magnetism in curved geometries, highlighting numerous peculiarities emerging from geometrically curved magnetic objects such as curved wires, shells, as well as complex three dimensional structures. Extending planar two dimensional structures into the three dimensional space has become a general trend in multiple disciplines across electronics, photonics, plasmonics and magnetics. This approach provides the means to modify conventional and even launch novel functionalities by tailoring the local curvature of an object. The book covers the theory of curvilinear micromagnetism as well as experimental studies of geometrically curved magnets including both fabrication and characterization. With its coverage of fundamental aspects, together with exploration of numerous applications across magnonics, bio engineering, soft robotics and shapeable magnetoelectronics, this edited collection is ideal for all scientists in academia and industry seeking an overview and wishing to keep abreast of advances in the novel field of curvilinear micromagnetism. It provides easy but comprehensive access to the field for newcomers, and can be used for graduate level courses on this subjec

A local view of the laser induced magnetic domain dynamics in CoPd stripe domains at the picosecond time scale

The dynamic of the magnetic structure in a well ordered ferromagnetic CoPd stripe domain pattern has been investigated upon excitation by femtosecond infrared laser pulses. Time-resolved X-ray magnetic circular dichroism in photoemission electron microscopy (TR-XMCD-PEEM) is used to perform real space magnetic imaging with 100 ps time resolution in order to show local transformations of the domains structures. Using the time resolution of the synchrotron radiation facility of the Helmholtz-Zentrum Berlin, we are able to image the transient magnetic domains in a repetitive pump and probe experiment. In this work, we study the reversible and irreversible transformations of the excited magnetic stripe domains as function of the laser fluence. Our results can be explained by thermal contributions, reducing the XMCD amplitude in each stripe domain below a threshold fluence of 12 mJ/cm2. Above this threshold fluence, irreversible transformations of the magnetic domains are observed. Static XMCD-PEEM images reveal the new partially ordered stripe domain structures characterized by a new local magnetic domain distribution showing an organized pattern at the micrometer scale. This new arrangement is attributed to the recovery of the magnetic anisotropy during heat dissipation under an Oersted field.Comment: 20 pages including 8 figures and 1 Tabl

Magnetically Capped Rolled up Nanomembranes

Modifying the curvature in magnetic nanostructures is a novel and elegant way toward tailoring physical phenomena at the nanoscale, allowing one to overcome limitations apparent in planar counterparts. Here, we address curvature driven changes of static magnetic properties in cylindrically curved magnetic segments with different radii of curvature. The curved architectures are prepared by capping nonmagnetic micrometer and nanometer sized rolled up membranes with a soft magnetic 20 nm thick permalloy Ni80Fe20 film. A quantitative comparison between the magnetization reversal processes in caps with different diameters is given. The phase diagrams of magnetic equilibrium domain patterns diameter versus length are generated. For this, joint experimental, including X ray magnetic circular dichroism photoelectron emission microscopy XMCD PEEM , and theoretical studies are carried out. The anisotropic magnetostatic interaction in cylindrically curved architectures originating from the thickness gradient reduces substantially the magnetostatic interaction between closely packed curved nanowires. This feature is beneficial for racetrack memory devices, since a much higher areal density might be achieved than possible with planar counterpart

5 Mechanical thrombectomy in acute ischemic stroke patients with low alberta stroke program early computed tomography scores

Background and purposeLimited data exists on the benefit of mechanical thrombectomy (MT) in acute ischemic stroke patients presenting with low ASPECTS (Alberta Stroke Program Early Computed Tomography (CT) Score). The aim of this substudy was investigate the outcome of low ASPECTS (0–5) patients undergoing mechanical thrombectomy in the Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke (STRATIS) Registry.MethodsData from the STRATIS Registry, a prospective, multicenter, non-randomized, observational study of AIS LVO patients treated with the Solitaire stent-retriever as the first choice therapy within 8 hours from symptoms onset, was used to identify patients with baseline ASPECTS 0–5. CT ASPECTS was adjudicated by a core lab blinded to clinical outcomes.ResultsA total of 57/763 (7.5%) patients had a baseline ASPECTS 0–5, of which 10 were ASPECTS 0–3 and 47 ASPECTS 4–5. Mean baseline NIHSS was 19.9±5.1. The majority of patients presented with ICA (42.1%) and M1 (47.4%) occlusions. IV-rtPA was administered in 68.4%. Mean onset to arterial puncture was 276±102.9 minutes and puncture to reperfusion time was 45.3±25.3 minutes. The majority of patients (85.5%) achieved substantial reperfusion (mTICI≥2b). Ninety-day outcome was reported in 52/57 (91.2%). The rate of good functional outcome (mRS≤2) was 28.8% (versus 59.7% in ASPECTS 6–10 group, p<0.001), which is higher than the 14.1% reported in the control arm 0–5 in the HERMES pooled analysis. Symptomatic intracranial hemorrhage and mortality rates were 7.0% and 30.8%, respectively. When further dichotomizing the group to ASPECTS 0–3 and 4–5 to determine the cut-off for MT futility, the rate of good outcome was 10% and 33.3%, respectively. In investigating the interaction between age and ASPECTS 0–5, low ASPECTS patients older than 75 had a lower rate of good clinical outcome than those 65–75 and less than 65 (0%, 18.2%, 44.8%).ConclusionIn the STRATIS Registry, low ASPECTS 0–5 is associated with lower functional outcomes in patients undergoing mechanical thrombectomy. Clinical outcome in low ASPECTS may be age dependent. Prospective studies are needed to understand the benefit of MT in this patient population.DisclosuresO. Zaidat: None. D. Liebeskind: None. A. Jadhav: None. S. Ortega-Gutierrez: None. V. Szeder: None. D. Haussen: None. D. Yavagal: None. M. Froehler: None. R. Jahan: None. T. Yao: None. N. Mueller-Kronast: None

Local electrical control of magnetic order and orientation by ferroelastic domain arrangements just above room temperature

International audienceFerroic materials (ferromagnetic, ferroelectric, ferroelastic) usually divide into domains with different orientations of their order parameter. Coupling between different ferroic systems creates new functionalities, for instance the electrical control of macroscopic magnetic properties including magnetization and coercive field. Here we show that ferroelastic domains can be used to control both magnetic order and magnetization direction at the nanoscale with a voltage. We use element-specific X-ray imaging to map the magnetic domains as a function of temperature and voltage in epitaxial FeRh on ferroelastic BaTiO 3. Exploiting the nanoscale phase-separation of FeRh, we locally interconvert between ferromagnetic and antiferromagnetic states with a small electric field just above room temperature. Imaging and ab initio calculations show the antiferromagnetic phase of FeRh is favoured by compressive strain on c-oriented BaTiO 3 domains, and the resultant magnetoelectric coupling is larger and more reversible than previously reported from macroscopic measurements. Our results emphasize the importance of nanoscale ferroic domain structure and the promise of first-order transition materials to achieve enhanced coupling in artificial multiferroics