Magnetic Nanostructures in Modern Technology: Spintronics, Magnetic MEMS and Recording

Product Description

A team of outstanding scientists in the field of modern magnetic nanotechnologies illustrates the state of the art in several areas of advanced magneto-electronic devices, magnetic micro-electromechanical systems and high density information storage technologies.

The physics and chemistry of nano-scale systems have made rapid advances and there are real prospects of translating exciting scientific findings into a new generation of processes and high technology products with a potential impact on several industrial sectors.

In particular the development of nano-structured magnetic materials plays a leading role in the increasing miniaturization of devices with superior performances. The application areas considered are:

i) “magneto-electronics”, where the control of electron spins in magnetic hetero-structures offers new and improved functionalities in devices of integrated digital electronics. Magnetic random access memories, MRAM are among the principal applications for new non-volatile RAM with fast dynamics, toward the pico-, femto-second range.

ii) “magnetic MEMS” (micro-electro-mechanical systems), which are the integration of mechanical and electro/ferromagnetic elements (micro-actuators and sensors) with conventional electronics MEMS, promise a revolution in several product categories. In fact the proposed integration enables the development of smart products, where sensors can gather information from the environment by measuring thermal, magnetic, electric, mechanical, biological chemical, optical characteristics and the electronic section processes the information and the actuator promotes the action realizing a complete control of the environment.

iii) “Magnetic recording” is a leading technology in the information storage domain and the most relevant application in the field of magnetics, showing surprising continuous progress over several decades towards the limit of terabit per square inch of areal density.

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Interacting Electrons in Nanostructures

Product Description
The exciting field of nanostructured materials offers many challenging perspectives for fundamental research and technological applications. The combination of quantum mechanics, interaction, phase coherence, and magnetism are important for understanding many physical phenomena in these systems. This book provides an overview of many aspects of interacting electrons in nanostructures, including such interesting topics as quantum dots, quantum wires, molecular electronics, dephasing, spintronics, and nanomechanics. The content refelcts the current research in this area and is written by leading experts in the field.

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Spintronics In Computing

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

 

RABIYA TANVEER.                                                               

LECTURER IN PHYSICS

CHAITANYA DEGREE AND P.G COLLEGE

HNK,WARANGAL,INDIA.

AFFILIATION:

1.NANO SCIENCE & TECHNOLOGY CONSORTIUM,

NOIDA,UP.INDIA.

2.PHOTONICS 21,EUROPEAN TECHNOLOGY PLATFORM. EMAIL:munaizag@gmail.com                      

 

 

 

Spintronic Materials and Technology

Product Description
Few books exist that cover the hot field of second-generation spintronic devices, despite their potential to revolutionize the IT industry.Compiling the obstacles and progress of spin-controlled devices into one source, Spintronic Materials and Technology presents an in-depth examination of the most recent technological spintronic developments.

Featuring contributions from active researchers and leading experts, the book chronicles the main research challenges in spintronics. It first depicts the different classes of materials systems currently under investigation for use in spintronic devices. The contributors also address issues concerning the operation of spintronic devices, such as the new principle for future devices that use spin-polarized current. This promises to enable switching of individual spin components of the device while avoiding crosstalk at the nanoscale. The book concludes with descriptions of both Si and III-V semiconductor-based spin transistors and the integration of spin technology with photonics.

The second-generation spintronic devices discussed in Spintronic Materials and Technology will not only improve the existing capabilities of electronic transistors, but will enable future computers to run faster and consume less power.

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Handbook of Nanoscience, Engineering, and Technology, Second Edition

Product Description
The ability to study and manipulate matter at the nanoscale is the defining feature of 21st-century science. The first edition of the standard-setting Handbook of Nanoscience, Engineering, and Technology saw the field through its infancy. Reassembling the preeminent team of leading scientists and researchers from all areas of nanoscience and nanotechnology along with several new pioneers, this second edition will guide the field through its burgeoning adolescence.

The phenomenal growth and staggering variety of applications of nanotechnology prevent any reference from providing a complete picture of the field. Instead, this edition surveys the most important areas, the most promising technologies, and the fastest-growing developments of current interest. In particular, it discusses fundamental theory of molecular and nanoelectronics, advanced fabrication technologies, modeling and simulation results, and novel molecular and nanoelectronic devices.

New chapters in the Second Edition explore…

The story of how the National Nanotechnology Initiative was born, where it is now, and where it is going

Molecular computing and processing platforms

Spin field effect transistors

Moletronics and spintronics

Nanoarchitectonics

Molecular machines

Magnetic manipulation applications in biomedical science

Biological- and chemical-mediated self-assembly

Nanomanufacturing

Nanotextile technologies

Nanofluidics for cell biology

Carbon nanostructures and nanocomposites

Accelerated design tools for nanophotonic devices

Nanoparticles for drug delivery

Remaining the definitive reference for nano researchers around the world, the Handbook of Nanoscience, Engineering, and Technology, Second Edition provides the signposts for blazers of the nano trail.

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