Spintronics

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The spintronics (from the words spin and electronics ), sometimes called spin electronics or Fluxtronik called, is a new area of research in nanoelectronics that is both part of the basic research is also particularly strong application-based as. Spintronics is based on the magnetic moment of the electron for information display and processing and not only on its electrical charge like conventional semiconductor electronics .

The older term magnetoelectronics also essentially means the use of the electron spin for information processing. In contrast, in the more general term spintronics, however, u. a. contain the knowledge that one spins not only with magnetic fields , but z. B. can also manipulate with electric fields .

Basics

Spintronics is based on the possibility of so-called spin injection in semiconductor materials , but also in organic or metallic materials, and the spin injection can e.g. B. be done from metal to semiconductor. Spin-injection can be used to generate spin-polarized currents in the materials mentioned. With the magnitude and direction of the expected spin value, these have further degrees of freedom that can be used as additional properties for the display of information.

Applications

One application of spintronics are hard disks with "spin valve" - thin-film - read heads that use the GMR effect (giant magnetoresistance) or TMR effect . The GMR effect makes it possible to detect very small magnetic domains and thus significantly increase the capacity of hard drives. In 2007 Albert Fert and Peter Grünberg were awarded the Nobel Prize in Physics for their discovery of the GMR effect .

Storage media: ferromagnetism versus antiferromagnetism

While the current applications work exclusively with ferromagnetic storage media and read or write heads in order to take advantage of the effects mentioned, antiferromagnetic materials have also been the subject of current research for some time (~ 2013 to 2014) , as bits 0 and 1 with antiferromagnetic material can be reproduced just as well as with ferromagnetic material. Instead of the usual assignment,

  • 0 ↦ "magnetization upwards" or
  • 1 ↦ "Magnetization downwards",

use something like:

  • 0 ↦ "vertically alternating spin configuration" or
  • 1 ↦ "horizontally alternating spin configuration".

Mathematically, this corresponds to the transition from the rotation group SO (3) to the associated relativistic superposition group, the "double group" SU (2).

The main advantages of using antiferromagnetic over ferromagnetic material are

  1. the insensitivity to stray fields and
  2. the order of magnitude shorter switching times.

literature

  • Oliver Morsch: The spin makes it possible . NZZ, No. 2306, September 6, 2006. online
  • Tomasz Dietl: Spintronics. Elsevier Acad. Press, Amsterdam 2008, ISBN 978-0-08-044956-2 .
  • David D. Awshalom: Spin electronics. Kluwer Academic, Dordrecht 2004, ISBN 1-4020-1802-9 .

See also

References and footnotes

  1. ↑ z. B. Tomas Jungwirth, announcement of a colloquium lecture at a Bavarian university ("Relativistic Approaches to Spintronics with Antiferromagnets") : [1]

Web links