Paul Scherrer Institute

About: Paul Scherrer Institute is a facility organization based out in Villigen, Switzerland. It is known for research contribution in the topics: Neutron & Large Hadron Collider. The organization has 9248 authors who have published 23984 publications receiving 890129 citations. The organization is also known as: PSI.

Current-driven dynamics and inhibition of the skyrmion Hall effect of ferrimagnetic skyrmions in GdFeCo films.

Abstract: Magnetic skyrmions are swirling magnetic textures with novel characteristics suitable for future spintronic and topological applications. Recent studies confirmed the room-temperature stabilization of skyrmions in ultrathin ferromagnets. However, such ferromagnetic skyrmions show an undesirable topological effect, the skyrmion Hall effect, which leads to their current-driven motion towards device edges, where skyrmions could easily be annihilated by topographic defects. Recent theoretical studies have predicted enhanced current-driven behavior for antiferromagnetically exchange-coupled skyrmions. Here we present the stabilization of these skyrmions and their current-driven dynamics in ferrimagnetic GdFeCo films. By utilizing element-specific X-ray imaging, we find that the skyrmions in the Gd and FeCo sublayers are antiferromagnetically exchange-coupled. We further confirm that ferrimagnetic skyrmions can move at a velocity of ~50 m s−1 with reduced skyrmion Hall angle, |θSkHE| ~ 20°. Our findings open the door to ferrimagnetic and antiferromagnetic skyrmionics while providing key experimental evidences of recent theoretical studies. Non-zero topological charge prevents the straight motion of ferromagnetic skyrmions and hinders their applications. Here, the authors report the stabilization and current-driven dynamics of skyrmions in GdFeCo films in which the ferrimagnetic skyrmions can move with high velocity and reduced skyrmion Hall angle.

Search for supersymmetry at the LHC in events with jets and missing transverse energy

Abstract: A search for events with jets and missing transverse energy is performed in a data sample of pp collisions collected at sqrt(s) = 7 TeV by the CMS experiment at the LHC. The analyzed data sample corresponds to an integrated luminosity of 1.14 inverse femtobarns. In this search, a kinematic variable, alphaT, is used as the main discriminator between events with genuine and misreconstructed missing transverse energy. No excess of events over the standard model expectation is found. Exclusion limits in the parameter space of the constrained minimal supersymmetric extension of the standard model are set. In this model, squark masses below 1.1 TeV are excluded at 95% CL. Gluino masses below 1.1 TeV are also ruled out at 95% CL for values of the universal scalar mass parameter below 500 GeV.

Controlled and Reproducible Domain Wall Displacement by Current Pulses Injected into Ferromagnetic Ring Structures

Abstract: In a combined numerical and experimental study, we demonstrate that current pulses of different polarity can reversibly and controllably displace a magnetic domain wall (DW) in submicrometer permalloy (NiFe) ring structures. The critical current densities for DW displacement are correlated with the specific spin structure of the DWs and are compared to results of micromagnetic simulations including a spin-torque term. Using a notch, an attractive local pinning potential is created for the DW resulting in a highly reproducible spin structure of the DW, critical for reliable current-induced switching.

Dimensionality Control of Electronic Phase Transitions in Nickel-Oxide Superlattices

Abstract: The competition between collective quantum phases in materials with strongly correlated electrons depends sensitively on the dimensionality of the electron system, which is difficult to control by standard solid-state chemistry. We have fabricated superlattices of the paramagnetic metal lanthanum nickelate (LaNiO 3 ) and the wide-gap insulator lanthanum aluminate (LaAlO 3 ) with atomically precise layer sequences. We used optical ellipsometry and low-energy muon spin rotation to show that superlattices with LaNiO 3 as thin as two unit cells undergo a sequence of collective metal-insulator and antiferromagnetic transitions as a function of decreasing temperature, whereas samples with thicker LaNiO 3 layers remain metallic and paramagnetic at all temperatures. Metal-oxide superlattices thus allow control of the dimensionality and collective phase behavior of correlated-electron systems.

The H1 detector at HERA

Abstract: General aspects of the H1 detector at the electron-proton storage ring HERA as well as technical descriptions of the magnet, luminosity system, trigger, slow-control, data acquisition and off-line data handling are given. The three major components of the detector, the tracking, calorimeter and muon detectors, will be described in a forthcoming article. The present paper describes the detector that was used from 1992 to the end of 1994. After this a major upgrade of some components was undertaken. Some performance figures from luminosity runs at HERA during 1993 and 1994 are given.