1,720,987 research outputs found
Logic based on magnetic tunnel junctions
No full textReiss G, Meyners D. Logic based on magnetic tunnel junctions. JOURNAL OF PHYSICS-CONDENSED MATTER. 2007;19(16):165220.Logic gate arrays are electronic devices delivering an output voltage which is a function of one, two or more input voltages. Usually, such circuits are made from CMOS subdevices ( transistors) which provide an output function defined by the layout of the device. Thus such logic gate arrays are not programmable after the production and, moreover, they are volatile because inputs and output lose the information after power shutdown. Here, we describe the use of magnetic tunnel junctions for the preparation of alternative logic gate arrays. These devices are nonvolatile, i.e. keep the inputs and output after power shutdown, and they are field programmable, i.e. the output function can be defined even 'on the fly' during the operation. Potential drawbacks such as scalability and reproducibility will be addressed and possible solutions for these problems will be discussed
Shape dependence of the magnetization reversal in sub-mu m magnetic tunnel junctions
No full textKoop H, Brueckl H, Meyners D, Reiss G. Shape dependence of the magnetization reversal in sub-mu m magnetic tunnel junctions. JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. 2004;272-276:E1475-E1476.In order to get access to resistance of very small junctions with lateral sizes down to 100 nm and below, we have set up a home-built conducting atomic force microscope which is able to contact the individual junctions with the tip and measure the tunnel magnetoresistance (TMR). The junctions are patterned by standard electron beam lithography. The influence of the element shape is investigated by analysing their switching behaviour in TMR minor loops and asteroids. In addition, numerical simulations of the magnetization reversal are carried out and compared to the experiment. (C) 2003 Elsevier B. V. All rights reserved
Reliability of field programmable magnetic logic gate arrays
No full textReiss G, Meyners D. Reliability of field programmable magnetic logic gate arrays. APPLIED PHYSICS LETTERS. 2006;88(4):043505.In concepts for logic circuits using hysteretic magnetoresistive effects, one gains advantages of magnetic thin-film elements, e.g., nonvolatility, radiation hardness and nondestructive readout. The requirements concerning reproducibility of resistance and magnetoresistance, however, are much more stringent than for memory applications. Using experimental data of magnetic logic circuits, we show that the variances of resistance and magnetoresistance, and the amplitude of the magnetoresistance, determine the yield of working logic gates. The current magnetoresistance of 75% for CoFeB/Al2O3 junctions is close to the minimum required value. More than 250% obtained with MgO barriers, however, will allow a fault tolerant production. (c) 2006 American Institute of Physics
Influence of boundary roughness on the magnetization reversal in submicron sized magnetic tunnel junctions
No full textMeyners D, Bruickl H, Reiss G. Influence of boundary roughness on the magnetization reversal in submicron sized magnetic tunnel junctions. JOURNAL OF APPLIED PHYSICS. 2003;93(5):2676-2680.The reproducible magnetic switching of submicron magnetic tunnel junctions' (MTJ's) is an important requirement for their application in highly integrated magnetic memory devices. We have investigated the switching of small MTJ's by atomic. and magnetic force microscopy (AFM/MFM) combined with micromagnetic numerical simulations. The latter are carried out with the real (AFM) shape as input mask, including the boundary roughness of the MTJ's. MFM reveals S-, C-, and K-shaped magnetization patterns for rectangular submicron sized junctions in saturation. In general, the magnetization loops and switching fields are different for individual junctions. The simulations show that the detailed boundary shape, which is specific for each junction, has a significant influence on the nucleation and location of domain walls and vortices, and hence, on the magnetic switching. (C) 2003 American Institute of Physics
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Arrays of magnetic tunnelling junctions for field programmable logic gates
No full textReiss G, Brueckl H, Meyners D, Richter R, Wecker J. Arrays of magnetic tunnelling junctions for field programmable logic gates. JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. 2004;272-276:E1497-E1498.In spin-logic, one gains the advantages of magnetic film elements, i.e. non-volatility, the possibility of fast operation, radiation hardness and non-destructive readout. Here, we experimentally demonstrate the feasibility of logic gate arrays, based on spin-dependent tunnelling elements, which can be separately programmed on-chip to form a logic OR, AND, NOR or NAND function. Key factors for the tunnelling junctions and the gate arrays as reproducibility of both the resistance and the magnetoresistance, TMR amplitude and switching behaviour are discussed and demonstrated. (C) 2003 Elsevier B. V. All rights reserved
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Submicron-sized magnetic tunnel junctions in field programmable logic gate arrays
No full textMeyners D, Rott K, Brückl H, Reiss G, Wecker J. Submicron-sized magnetic tunnel junctions in field programmable logic gate arrays. JOURNAL OF APPLIED PHYSICS. 2006;99(2):023907.We experimentally demonstrate the feasibility of reprogrammable logic gate arrays with lateral dimensions down to 10x10 mu m(2). The gates are based on magnetic tunnel junctions which are elliptically patterned by e-beam lithography with sizes down to 200x100 nm(2). The junctions are realized with different tunneling systems and are investigated magnetically and electrically, where the magnetization reversal of the junctions' soft magnetic layer is done via currents in conducting lines. The switching currents could be reduced by a factor of about 2 by introducing an additional NiFe layer on top of the lines. Thus it is possible to use these gate arrays within a highly integrated environment. (c) 2006 American Institute of Physics
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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