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Davies J.E.,Nve Corporation | Gilbert D.A.,University of California at Davis | Mohseni S.M.,KTH Royal Institute of Technology | Mohseni S.M.,NanOsc AB | And 5 more authors.
Applied Physics Letters | Year: 2013

We have observed distinct temperature-dependent magnetization reversal modes in a perpendicular (Co/Pd)4/Co/Cu/(Co/Ni)4/Co pseudo-spin-valve, which are correlated with spin-transport properties. At 300 K, magnetization reversal occurs by vertically correlated domains. Below 200 K the hysteresis loop becomes bifurcated due to laterally correlated reversal of the individual stacks. The magnetic configuration change also leads to higher spin disorders and a significant increase in the giant magnetoresistance effect. First order reversal curve measurements reveal that the coupled state can be re-established through field cycling and allow direct determination of the interlayer coupling strength as a function of temperature. © 2013 AIP Publishing LLC.

Agency: Cordis | Branch: H2020 | Program: SGA-RIA | Phase: FETFLAGSHIP | Award Amount: 89.00M | Year: 2016

This project is the second in the series of EC-financed parts of the Graphene Flagship. The Graphene Flagship is a 10 year research and innovation endeavour with a total project cost of 1,000,000,000 euros, funded jointly by the European Commission and member states and associated countries. The first part of the Flagship was a 30-month Collaborative Project, Coordination and Support Action (CP-CSA) under the 7th framework program (2013-2016), while this and the following parts are implemented as Core Projects under the Horizon 2020 framework. The mission of the Graphene Flagship is to take graphene and related layered materials from a state of raw potential to a point where they can revolutionise multiple industries. This will bring a new dimension to future technology a faster, thinner, stronger, flexible, and broadband revolution. Our program will put Europe firmly at the heart of the process, with a manifold return on the EU investment, both in terms of technological innovation and economic growth. To realise this vision, we have brought together a larger European consortium with about 150 partners in 23 countries. The partners represent academia, research institutes and industries, which work closely together in 15 technical work packages and five supporting work packages covering the entire value chain from materials to components and systems. As time progresses, the centre of gravity of the Flagship moves towards applications, which is reflected in the increasing importance of the higher - system - levels of the value chain. In this first core project the main focus is on components and initial system level tasks. The first core project is divided into 4 divisions, which in turn comprise 3 to 5 work packages on related topics. A fifth, external division acts as a link to the parts of the Flagship that are funded by the member states and associated countries, or by other funding sources. This creates a collaborative framework for the entire Flagship.

Agency: Cordis | Branch: FP7 | Program: CP | Phase: ICT-2009.3.1 | Award Amount: 4.14M | Year: 2010

MACALO has two main deliverables, one in software and one in hardware which form the core business of the two European high-tech companies in the consortium. The MACALO consortium consists of pioneers of MAgnetoCALOritronics who cover the complete chain from SME start-up company innovation in hardware and software, device simulation and fabrication, benchmark measurements, computational materials science, and basic science, who are committed to employ their expertise to realize the main objectives. The primary goals of MACALO are\n\n1)\tto produce a working prototype of a computer simulation tool to help optimise integrated magnetoelectronic device design parameters at the nanoscale and\n\n2)\tdesign and prototype nano-scale magnetoelectronic RF oscillators with different combinations of desirable properties, optimisable subsequently (through further company research) for specific applications in wireless communication devices.\n\nAchieving these goals assists replacing the current systems of YIG oscillators, MRAM, and transistors with next generation magnetoelectronic Spin Torque Oscillators, ST-RAM, and transistors by finding material combinations, currently based on suboptimal experimental trial and error systems, using a set of theories, principles, tools and methods that accelerate the development of new devices with improved/optimised properties.\n\nManaging the increased heat and noise in the next generation of electronics is a great challenge. MAgneto CALOitronics (MACALO) addresses the modelling and control of the generation and flow of heat in beyond-CMOS magnetoelectronics circuits and devices. The results are relevant for thermal management of conventional CMOS and novel architectures beyond-CMOS such as low power, low-noise devices, thermally assisted memory devices, and interconnects.

Dumas R.K.,Gothenburg University | Iacocca E.,Gothenburg University | Bonetti S.,Stanford University | Sani S.R.,KTH Royal Institute of Technology | And 10 more authors.
Physical Review Letters | Year: 2013

It has been argued that if multiple spin wave modes are competing for the same centrally located energy source, as in a nanocontact spin torque oscillator, that only one mode should survive in the steady state. Here, the experimental conditions necessary for mode coexistence are explored. Mode coexistence is facilitated by the local field asymmetries induced by the spatially inhomogeneous Oersted field, which leads to a physical separation of the modes, and is further promoted by spin wave localization at reduced applied field angles. Finally, both simulation and experiment reveal a low frequency signal consistent with the intermodulation of two coexistent modes. © 2013 American Physical Society.

Mohseni S.M.,KTH Royal Institute of Technology | Mohseni S.M.,NanOsc AB | Sani S.R.,KTH Royal Institute of Technology | Sani S.R.,NanOsc AB | And 7 more authors.
Physica Status Solidi - Rapid Research Letters | Year: 2011

We demonstrate a nano-contact based spin-torque oscillator (STO) combining a high operating frequency with low field operation. The STO is based on an orthogonal spin-valve architecture with an in-plane Co polarizer and an out-of-plane Co/Ni multilayer free layer. High frequency operation at low external fields is achieved by tailoring the Co/Ni layer properties to increase the strength (Hk) of the perpendicular magnetic anisotropy, while simultaneously reducing the saturation magnetization (Ms). Our approach emphasizes the importance of μ0(Hk-Ms) in determining the operating frequency in this system, and suggests that yet higher frequencies should be attainable through further optimization. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) In this Letter the authors demonstrate a nanocontact spin-torque oscillator (STO) based on an orthogonal spin-valve architecture with an in-plane Co polarizer and an out-of-plane Co/Ni multilayer free layer. High frequency operation at low external fields is achieved by tailoring the Co/Ni layer properties to increase the strength of the perpendicular magnetic anisotropy, while simultaneously reducing the saturation magnetization. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sani S.,KTH Royal Institute of Technology | Sani S.,NanOsc AB | Persson J.,NanOsc AB | Mohseni S.M.,KTH Royal Institute of Technology | And 11 more authors.
Nature Communications | Year: 2013

Spin-torque oscillators offer a unique combination of nanosize, ultrafast modulation rates and ultrawide band signal generation from 100 MHz to close to 100 GHz. However, their low output power and large phase noise still limit their applicability to fundamental studies of spin-transfer torque and magnetodynamic phenomena. A possible solution to both problems is the spin-wave-mediated mutual synchronization of multiple spin-torque oscillators through a shared excited ferromagnetic layer. To date, synchronization of high-frequency spin-torque oscillators has only been achieved for two nanocontacts. As fabrication using expensive top-down lithography processes is not readily available to many groups, attempts to synchronize a large number of nanocontacts have been all but abandoned. Here we present an alternative, simple and cost-effective bottom-up method to realize large ensembles of synchronized nanocontact spin-torque oscillators. We demonstrate mutual synchronization of three high-frequency nanocontact spin-torque oscillators and pairwise synchronization in devices with four and five nanocontacts. © 2013 Macmillan Publishers Limited. All rights reserved.

Houshang A.,Gothenburg University | Houshang A.,NanOsc AB | Iacocca E.,Gothenburg University | Iacocca E.,NanOsc AB | And 7 more authors.
Nature Nanotechnology | Year: 2016

The synchronization of multiple nanocontact spin-torque oscillators (NC-STOs) is mediated by propagating spin waves (SWs). Although it has been shown that the Oersted field generated in the vicinity of the NC can dramatically alter the emission pattern of SWs, its role in the synchronization behaviour of multiple NCs has not been considered so far. Here we investigate the synchronization behaviour in multiple NC-STOs oriented either vertically or horizontally, with respect to the in-plane component of the external field. Synchronization is promoted (impeded) by the Oersted field landscape when the NCs are oriented vertically (horizontally) due to the highly anisotropic SW propagation. Not only is robust synchronization between two oscillators observed for separations larger than 1,000nm, but synchronization of up to five oscillators, a new record, has been observed in the vertical array geometry. Furthermore, the synchronization can no longer be considered mutual in nature. © 2016 Macmillan Publishers Limited.

Mohseni S.M.,KTH Royal Institute of Technology | Mohseni S.M.,NanOsc AB | Dumas R.K.,Gothenburg University | Fang Y.,Gothenburg University | And 7 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The temperature-dependent coupling mechanisms in perpendicular pseudo-spin valves based on the following structure, [Ni/Co]5/Cu(t Cu)/[Ni/Co]2, are investigated. Despite a thick (t Cu 3nm) Cu spacer, room-temperature measurements reveal complete coupling of the [Ni/Co]5 and [Ni/Co]2 multilayers. This coupling can be attributed to strong long range magnetostatic stray fields that penetrate the spacer layer. This results in magnetic domain imprinting and vertically correlated domains throughout the reversal process. Surprisingly, when the temperature is reduced, a complete decoupling is observed. This somewhat counterintuitive result can be explained by a large difference in the [Ni/Co]5 and [Ni/Co]2 multilayer coercivities at reduced temperatures, which then impedes domain imprinting and promotes decoupling. Finally, the decoupling temperature is found to increase with spacer thickness. © 2011 American Physical Society.

Anh Nguyen T.N.,KTH Royal Institute of Technology | Benatmane N.,KTH Royal Institute of Technology | Fallahi V.,KTH Royal Institute of Technology | Fang Y.,Gothenburg University | And 6 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2012

By varying the Pd thickness (t Pd) from 0 to 8 nm in [Co/Pd] 4/Co/Pd(t Pd)/NiFe exchange springs, we demonstrate (i) continuous tailoring of the exchange coupling between a [Co/Pd] 4/Co layer with perpendicular anisotropy, and a NiFe layer with an in-plane easy axis, (ii) tuning of the NiFe out-of-plane magnetization angle from 20 ○ to 80 ○, and (iii) an up to two-fold increase in the NiFe damping. The partial decoupling also results in a highly uniform NiFe magnetization. These properties make [Co/Pd] 4/Co/Pd(t Pd)/NiFe spring magnets ideal candidates for use as tilted polarizers, by combining stable and well-defined spin directions of its carriers with a high degree of angular freedom. © 2012 Elsevier B.V.

Agency: Cordis | Branch: FP7 | Program: CP | Phase: ICT-2011.3.1 | Award Amount: 4.82M | Year: 2013

Innovative components and systems based on nano-engineered semiconductor, magnetic or insulating materials will be the driving force for the micro- and nano-electronics industry of the 21st century. For telecommunications systems, but also for data storage and Automation, Control and Security applications, alternative More than MOORE paths to systems are provided by nano-scale microwave spintronics components due to (i) their unique spin polarized transport properties that appear only at nanoscale dimensions (<100nm lateral, and 2-5 nm vertical), (ii) their unique (multifunctional) microwave properties including signal generation, processing and detection and (iii) their compatibility with CMOS technology. Going beyond previous fundamental research on spintronics devices, this project will target technological breakthroughs not only to generate, but also to process (mix, modulate, synchronise) and to detect microwave frequencies. Based on innovative spin transfer devices, four discrete systems will be developed that address bottlenecks of current technologies: A Wireless Telecommunications 1: Ultrawideband frequency synthesis provided by spintronics microwave components with novel circuit design on CMOS for realization of an adapted phase locked loop; B Wireless Telecommunications 2: Ultrafast frequency detection using frequency discriminating level detection; C Data storage: Novel dynamic readout schemes for detecting frequency shifts implemented for realization of high data rate read heads; D Automation control & security : Broad bandwidth, high slew rate proximity sensor based on frequency generation and modulation capabilities.\nThe broader objective is to bring the device level knowledge acquired in the past years by the partners towards systems as a first crucial step towards industrialization, warranting the leading position not only of European research but also of European industry in microwave spintronics.

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