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55 results on '"C. S. Davies"'

52. Integration platform for optical switching of magnetic elements

Author

Martijn J. R. Heck, Ricardo M. Sousa, Theo Rasing, Farshad Moradi, Clemens J. Kruckel, A. Olivier, Hanna Becker, Elzbieta K. Sobolewska, Andrei Ivanovitch Kiriliouk, Johan Pelloux-Prayer, Luis Avilés Félix, G. Li, C. S. Davies, Dries Van Thourhout, Ioan Lucian Prejbeanu, Aarhus University [Aarhus], Radboud University [Nijmegen], Interuniversity Microelectronics Centre (IMEC), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), European Project: 713481,SPICE, Subramania, Ganapathi S., Foteinopoulou, Stavroula, Radboud university [Nijmegen], Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Technology and Engineering, Physics::Optics, Optical power, 02 engineering and technology, 7. Clean energy, 01 natural sciences, Optical switch, magnetic memory, Stack (abstract data type), 0103 physical sciences, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Absorption (electromagnetic radiation), spintronic, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, Magnetoresistive random-access memory, photonic, integrated photonics, business.industry, terbium, Finite-difference time-domain method, all-optical switching, 021001 nanoscience & nanotechnology, cobalt, Tunnel magnetoresistance, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, Photonics, 0210 nano-technology, business
Abstract

We present a detailed investigation of a novel platform for integration of spintronic memory elements and a photonic network, for future ultrafast and energy-efficient memory. We designed and fabricated magnetic tunnel junction (MTJ) structures based on (Tb/Co)x5 multilayer stack with optically switchable magnetization. Optical single-pulse measurements allowed us to estimate the value of the stray field present in the parallel configuration, which prevents the structure from all-optical switching. We performed numerical calculations based on the Finite Difference Time Domain method and ellipsometry measurements of (Tb/Co)x5 to compute the absorption by the MTJ structure. Simulation results are in good agreement with the experimental measurements, where we implemented a thermal model to estimate effective absorption in the pillar. These estimations showed up to 14% absorption of the incident optical power in 300-nm-wide MTJ. Moreover, we designed and realized an integrated optical network with focusing structures to efficiently guide and couple the light into the MTJs. We show a chain of necessary steps to obtain the threshold value of the switching energy, and our results presenting a path forward for full system integration of optically switchable MRAM technology

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55. Formation of the band spectrum of spin waves in 1D magnonic crystals with different types of interfacial boundary conditions.

Author

V V Kruglyak, C S Davies, V S Tkachenko, O Yu Gorobets, Yu I Gorobets, and A N Kuchko

Subjects
SPIN waves, THIN film devices, MAGNONS
Abstract

We report a theoretical study of the spin-wave band spectrum of magnonic crystals formed by stacking thin-film magnetic layers, with general assumptions about the properties of the interfaces between the layers. The use of the Barnaś–Mills magnetization boundary conditions has enabled us to systematically trace the origin of the magnonic band gaps in the spin-wave spectrum of such systems. We find that the band gaps are a ubiquitous attribute of a weakened interlayer coupling and a finite interface anisotropy (pinning). The band gaps in such systems represent a legacy of the discrete spin-wave spectrum of the individual magnetic layers periodically stacked to form the magnonic crystal rather than resulting from Bragg scattering. At the same time, magnonic crystals with band gaps due to the Bragg scattering can be described by natural boundary conditions (i.e. those maintaining continuity of the magnetization direction across the whole sample). We generalize our conclusions to systems beyond thin-film magnonic crystals and propose magnonic crystals based on the ideas of graded-index magnonics and those formed by Fano resonances as a possible way to circumvent the discovered issues. [ABSTRACT FROM AUTHOR]

Published
2017
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