Intel Unveils New Product Plans for High-Performance Computing
June 3, 2010 by AboutNanoWires.com · Leave a Comment
Intel Unveils New Product Plans for High-Performance Computing
During the International Supercomputing Conference (ISC), Intel Corporation announced plans to deliver new products based on the Intel Many Integrated Core (MIC) architecture that will create platforms running at trillions of calculations per second, while also retaining the benefits of standard Intel processors.
Read more on PhysOrg
‘Quantum dot’ promises super-fast, super-powerful computing
May 30, 2010 by AboutNanoWires.com · Leave a Comment
‘Quantum dot’ promises super-fast, super-powerful computing
Australian scientists have developed a new transistor in a computer chip that is 10 times smaller than those currently in use.
Read more on Sify News
Spintronics In Computing
May 27, 2010 by AboutNanoWires.com · Leave a Comment
Spintronics in computing
Spintronics is an emerging technology that exploits the intrinsic spin of the electron and its associated magnetic moment.
In 1980s the experiments on spin-dependent electron transport phenomena in solid-state devices donerevealed the research field of spintronics.It includes the observation of spin-polarized electron injection from a ferromagnetic metal to a normal metal.
Electrons are spin-1/2 fermions .Fermion constitute a two-state system with spin “up” and spin “down”. A current of spin-polarized electrons comprising more of one spin species—up or down ,is the primary requirement of spintronic devices .SO we require the devices spin injectors and a separate system that is sensitive to the spin polarization of the electrons (spin detector). Manipulation of the electron spin during transport between injector and detector (especially in semiconductors) via spin precession can be accomplished using real external magnetic fields or effective fields caused by spin-orbit interaction
Spin pol arization in non-magnetic materials can be achieved either through the Zeeman effect in large magnetic fields and low temperatures, or by non-equilibrium methods. In the latter case, the non-equilibrium polarization will decay over a timescale called the “spin lifetime”. Spin lifetimes of conduction electrons in metals are relatively short (<1nsec) but in semiconductors the lifetimes can be very long (µsec at low temperatures), especially when the electrons are isolated in local trapping potentials .
Metals-based spintronic devices
The simplest method of generating a spin-polarised current in a metal is to pass the current through a ferromagnetic material. This effect is useful in a giant magnetoresistance (GMR) device. A GMR device consists of at least two layers of ferromagnetic materials separated by a spacer layer. When the two magnetization vectors of the ferromagnetic layers are aligned, the electrical resistance will be lower (so a higher current flows at constant voltage) than if the ferromagnetic layers are anti-aligned. This constitutes a magnetic field sensor.ie the device can acts as inverter with logic 0 or logic1.
Two variants of GMR have been applied in devices:
(1) current-in-plane (CIP), where the electric current flows parallel to the layers and
(2) current-perpendicular-to-plane (CPP), where the electric current flows in a direction perpendicular to the layers.
Other metals-based spintronics devices:
Tunnel Magnetoresistance (TMR):In this device CPP transport is achieved by using quantum-mechanical tunneling of electrons through a thin insulator separating ferromagnetic layers.
Spin Torque Transfer,:In this a current of spin-polarized electrons is used to control the magnetization direction of ferromagnetic electrodes in the device.
Semiconductor-based spintronic devices
The spin-polarized electrons are generated via optical orientation using circularly-polarized photons at the bandgap energy incident on semiconductors with appreciable spin-orbit interaction (like GaAs and ZnSe). Although electrical spin injection can be achieved in metallic systems by simply passing a current through a ferromagnet, the large impedance mismatch between ferromagnetic metals and semiconductors prevented efficient injection across metal-semiconductor interfaces. A solution to this problem is to use ferromagnetic semiconductor sources (like manganese-doped gallium arsenide GaMnAs), increasing the interface resistance with a tunnel barrier, or using hot-electron injection.
Spin detection in semiconductors is another challenge, which has been met with the following techniques:
Faraday/Kerr rotation of transmitted/reflected photons
Circular polarization analysis of electroluminescence
Nonlocal spin valve (adapted from Johnson and Silsbee’s work with metals
Ballistic spin filtering
The latter technique was used to overcome the lack of spin-orbit interaction and materials issues to achieve spin transport in silicon, the most important semiconductor for electronics.
Because external magnetic fields can cause large Hall effects and magnetoresistance in semiconductors , the only conclusive evidence of spin transport in semiconductors is demonstration of spin precession and dephasing in a magnetic field non-collinear to the injected spin orientation. This is called the Hanle effect.
Applications spintronic devices
The storage density of hard drives is rapidly increasing along an exponential growth curve, in part because spintronics-enabled devices like GMR and TMR sensors have increased the sensitivity of the read head which measures the magnetic state of small magnetic domains (bits) on the spinning platter. The doubling period for the areal density of information storage is twelve months, much shorter than Moore’s Law, which observes that the number of transistors that can cheaply be incorporated in an integrated circuit doubles every two years.
Racetrack memory
MRAM, or magnetic random access memory, uses a grid of magnetic storage elements called magnetic tunnel junctions (MTJ’s). MRAM is nonvolatile so information is stored even when power is turned off, potentially providing instant-on computing. Motorola has developed a 1st generation 256 kb MRAM based on a single magnetic tunnel junction and a single transistor and which has a read/write cycle of under 50 nanoseconds .
Racetrack memory, encodes information in the direction of magnetization between
domain walls of a ferromagnetic metal wire.
4.Advantages of semiconductor-based spintronics applications are potentially lower power use and a smaller footprint than electrical devices used for information processing Also, applications such as semiconductor lasers using spin-polarized electrical injection have shown threshold current reduction and controllable circularly polarized coherent light output. Future applications may include a spin-based having advantages over MOSFET devices such as steeper sub-threshold slope.
References
^ IBM RD 50-1 | Spintronics—A retrospective and perspective
^ Physics Profile: “Stu Wolf: True D! Hollywood Story”
^ http://prola.aps.org/pdf/PRL/v55/i17/p1790_1
^ Phys. Rev. Lett. 61 (1988): M. N. Baibich, J. M. Broto, A. Fert, F. Nguyen Van Dau, F. Petroff, P. Eitenne, G. Creuzet, A. Friederich, and J. Chazelas – Giant Magnetoresistanc…
^ http://prola.aps.org/pdf/PRB/v39/i7/p4828_1
^ PII: 0370-1573(94)90105-8
^ http://www.sciencedirect.com/science/article/B6TVM-46R3N46-10D/2/90703cfc684b0679356dce9a76b2e942
^ Cookies Required
^ http://www.sigmaaldrich.com/materials-science/alternative-energy-materials/magnetic-materials/tutorial/spintronics.html
^ http://www.everspin.com/technology.html
^ The Emergence of Practical MRAM http://www.crocus-technology.com/pdf/BH GSA Article.pdf
^ http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=218000269
^ Phys. Rev. B 62 (2000): B. T. Jonker, Y. D. Park, B. R. Bennett, H. D. Cheong, G. Kioseoglou, and A. Petrou – Robust electrical spin injection
^ Cookies Required
^ Phys. Rev. Lett. 90 (2003): X. Jiang, R. Wang, S. van Dijken, R. Shelby, R. Macfarlane, G. S. Solomon, J. Harris, and S. S. Parkin – Optical Detection of Hot-Electron
^ Phys. Rev. Lett. 80 (1998): J. M. Kikkawa and D. D. Awschalom – Resonant Spin Amplification in
^ Polarized optical emission due to decay or recombination of spin-polarized injected carriers – US Patent 5874749
^ Electrical detection of spin transport in lateral ferromagnet-semiconductor devices : Abstract : Nature Physics
^ Electronic measurement and control of spin transport in silicon : Abstract : Nature
^ Access : : Nature
^ Access : : Nature
^ Cookies Required
Further reading
“Introduction to Spintronics”. Marc Cahay, Supriyo Bandyopadhyay, CRC Press, ISBN 0-8493-3133-1
Ultrafast Manipulation of Electron Spin Coherence. J. A. Gupta, R. Knobel, N. Samarth and D. D. Awschalom in Science, Vol. 292, pages 2458-2461; June 29, 2001.
Spintronics: A Spin-Based Electronics Vision for the Future. S. A. Wolf et al., Science 294, 1488-1495 (2001)
How to Create a Spin Current. P. Sharma, Science 307, 531-533 (2005)
Search Google Scholar for highly cited articles with query: spintronics OR magnetoelectronics OR “spin based electronics”
“Electron Manipulation and Spin Current”. D. Grinevich. 3rd Edition, 2003.*
Semiconductor Spintronics. J. Fabian, A. Matos-Abiague, C. Ertler, P. Stano, and I. Žuti?, Acta Phys. Slovaca 57, 565-907 (2007)
Spintronics: Fundamentals and Applications. I. Žuti?, J. Fabian, and S. Das Sarma, Rev. Mod. Phys. 76, 323-410 (2004)
External links
“Spintronics”. Scientific American. June 2002. http://www.sciam.com/article.cfm?articleID=0007A735-759A-1CDD-B4A8809EC588EEDF.
RaceTrack:InformationWeek (April 11, 2008)
IBM (2003)
Wired: update on MRAMs, 2003 Jul
Spintronics research targets GaAs.
Spintronics at Indian Institute of Science, Bangalore, India
Spintronics at SUNY Albany’s College of Nanoscale Science and Engineering
Spintronics information community site
IBM to use ‘spintronics’ to increase computer memory capacity (April 12, 2008)
Semiconductor spintronics lab at University of Maryland
Spintronics Tutorial
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Quantum Computing Devices: Principles, Designs, and Analysis
May 27, 2010 by AboutNanoWires.com · 1 Comment
Product Description
One of the first books to thoroughly examine the subject, Quantum Computing Devices: Principles, Designs, and Analysis covers the essential components in the design of a “real” quantum computer. It explores contemporary and important aspects of quantum computation, particularly focusing on the role of quantum electronic devices as quantum gates.
Largely self-contained and written in a tutorial style, this reference presents the analysis, design, and modeling of the major types of quantum computing devices: ion traps, cavity quantum electrodynamics (QED), linear optics, quantum dots, nuclear magnetic resonance (NMR), superconducting quantum interference devices (SQUID), and neutral atom traps. It begins by explaining the fundamentals and algorithms of quantum computing, followed by the operations and formalisms of quantum systems. For each electronic device, the subsequent chapters discuss physical properties, the setup of qubits, control actions that produce the quantum gates that are universal for quantum computing, relevant measurements, and decoherence properties of the systems. The book also includes tables, diagrams, and figures that illustrate various data, uses, and designs of quantum computing.
As nanoelectronics will inevitably replace microelectronics, the development of quantum information science and quantum computing technology is imperative to the future of information science and technology. Quantum Computing Devices: Principles, Designs, and Analysis helps fulfill this need by providing a comprehensive collection of the most promising devices for the future.
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Robust Computing with Nano-scale Devices: Progresses and Challenges
May 25, 2010 by AboutNanoWires.com · Leave a Comment
Product Description
Robust Nano-Computing focuses on various issues of robust nano-computing, defect-tolerance design for nano-technology at different design abstraction levels. It addresses both redundancy- and configuration-based methods as well as fault detecting techniques through the development of accurate computation models and tools. The contents present an insightful view of the ongoing researches on nano-electronic devices, circuits, architectures, and design methods, as well as provide promising directions for future research.
BUY FROM AMAZON–>> Robust Computing with Nano-scale Devices: Progresses and Challenges
