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Spintronic Materials

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1) Wide bandgap. suited for applications with short wavelength light ... Wide band gap hence transparency. 2) Good piezoelectric and electrooptic material. ... – PowerPoint PPT presentation

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Title: Spintronic Materials


1
Spintronic Materials
2
Overview
  • Electrons have, In addition to their mass and
    charge, an intrinsic quality of angular momentum
    called spin.
  • Associated with the spin is a magnetic field.
  • Scientists represent the spin as a vector (up or
    down).
  • In a magnetic field, electrons with spin up and
    spin down states have different energies.
  • In an ordinary electric circuit, the spins are
    oriented at random and have no effect on current
    flow.
  • But the spintronic devices create spin- polarized
    currents and use the spin to control current flow
    (Magnetoresistance).

3
Present Information Technology
  • The charge, mass and spin of electrons form the
    foundation of present information technology.
  • The integrated circuits used for information
    processing (like CPU unit), use only the charge
    of electrons. These circuits use transistors that
    work by transfer of electrons.
  • Storage of information is done by magnetic
    recording using the spin of electrons.

4
  • Electron charge Spin
    Spintronics
  • Electrons charge and spin can be merged together
    to form a new class of electronics called
    Spintronics.
  • Data storage and information processing can be
    combined in a single device by exploiting spin
    and charge degrees of freedom of electrons
    simultaneously.
  • Spintronic devices will be smaller, more
    versatile and more robust than those currently
    making up silicon chips and circuit elements.

5
Why Semiconductor Spintronics? He who controls
magnetism (in semicomductor)
rules the world
  • Possible Revolutionary Advances
  • Fast, very dense memory and logic at extremely
    low power.
  • Spin Quantum Devices (Spin FETs, LEDs, RTDs).
  • Quantum computing.
  • Complete computer on a chip.

6
What is needed?
  • Ferromagnetic Materials at high Temperatures
    (semiconductors)
  • Spin Polarizers\Aligners
  • Spin injectors (and long spin lifetime)
  • Means injectors

7
First ferromagnetic SemiconductorsIII1-XMnXV
Random Alloys(InMnAs and GaMnAs)
  • All III1-XMnXV are heavily p-type
  • Mn is dopant (acceptor) in III-V

8
Advantages of Oxide Semiconductors
  • 1) Wide bandgap
  • suited for applications with short
    wavelength light
  • 2) Transparency and dyeability with pigments
  • 3) High n-type carrier concentration
  • - Capability to be grown at low temperatures
    even on plastic substrates.
  • 4) Ecological safety and durability
  • 5) low cost, etcand!
  • large electronegativity of oxygen expected
    to produce
  • strong p-d exchange coupling between band
    carriers and
  • localized spins
  • SUCH advantages make oxide semiconductors
    attractive!

9
Afew materials exhibiting room temperature
ferromagnetism
10
Mn doped ZnOIt is the most promising material to
make a ferromagnetic semiconductor
  • 1) Solubility of Mn in ZnO is larger than 10
    mol
  • 2) Amount of injected spins in the host material
    can be very large with Mn doping.
  • 3) Mn is anitiferromagnetic, which makes this
    system more clean in terms of metal precipitate
    induced ferromagnetism
  • 4) Theories predicted a possibilty of above room
    temperature ferromagnetism in Mn doped system
    doped with holes.(Dietl et al.)

11
Host ZnO has numerous interesting properties and
wide range of applications
  • Wide band gap hence transparency
  • 2) Good piezoelectric and electrooptic
    material.
  • 3) Low cost, easily deposited on variety of
    substrates, and environmental friendly

12
Thank You
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