University College Of Engineering, Rajasthan Technical University, Kota.

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University College Of Engineering,
Rajasthan Technical University, Kota.
Presentation On
Spintronics Technology
Submitted To Presented By Dr R S
Meena Shailendra Kumar Singh Mr
Pankaj Shukla C.R. No
07/126 Final B. Tech. (ECE)
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What Is Spintronics ?

• In conventional electronics, electron charge is
  used for manipulation, storage, and transfer of
  information .
• Spintronics uses electron spins in addition to
  or in place of the electron charge.

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Why We Need Spintronics !

• Failure of Moores Law
• Moores Law states that the number of
  transistors on a
• silicon chip will roughly double every
  eighteen months.
• But now the transistors other components have
  reached
• nanoscale dimensions and further reducing
• the size would lead to
• 1. Scorching heat making making the
  circuit inoperable.
• 2. Also Quantum effects come into play at
  nanoscale
• dimensions.
• So the size of transistors other components
  cannot be
• reduced further.

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Basic Principle

• In Spintronics , information is carried by
  orientation of
• spin rather than charge.
• Spin can assume one of the two states relative
  to the magnetic
• field, called spin up or spin down.
• These states, spin up or spin down, can be used
  to represent
• 1 and 0 in binary logic.
• In certain spintronic materials, spin
  orientation can be used
• as spintronic memory as these orientation do
  not change
• when system is switched off.

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Advantage Spintronics

• Low power consumption.
• Less heat dissipation.
• Spintronic memory is non-volatile.
• Takes up lesser space on chip, thus more
  compact.
• Spin manipulation is faster , so greater read
  write speed.
• Spintronics does not require unique and
  specialized semiconductors.
• Common metals such as Fe, Al, Ag , etc. can
  be used.

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Gaint Magnetoresistance (GMR)

• The basic GMR device consists of a layer of non
  -magnetic metal between two
• two magnetic layers.
• A current consisting of spin-up and spin-down
  electrons is passed through
• the layers.
• Those oriented in the same direction as the
  electron spins in a magnetic layer pass
• through quite easily while those oriented
  in the opposite direction are scattered.

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SPIN VALVES

• If the orientation of one of the magnetic layers
  be changed then
• the device will act as a filter, or spin
  valve, letting through more
• electrons when the spin orientations in the
  two layers are the same
• and fewer when orientations are oppositely
  aligned.
• The electrical resistance of the device can
  therefore be changed
• dramatically.

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Tunnel Magnetoresistance

• Magnetic tunnel junction has two
• magnetic layers separated by an insulating
• metal-oxide layer.
• Is similar to a GMR spin valve except that
• a very thin insulator layer is sandwitched
• between magnetic layers instead of metal
• layer .
• The difference in resistance between the
• spin-aligned and nonaligned cases is much
• greater than for GMR device infact 1000
• times higher than the standard spin valve.

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Magnetoresistive Random Access Memory (MRAM)

• MRAM uses magnetic storage elements.
• The elements are mostly tunnel junctions formed
  from two
• ferromagnetic plates, each of which can hold
  a magnetic field,
• separated by a thin insulating layer.

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SRAM VS DRAM VS MRAM
SRAM DRAM MRAM

• Advantage
• Fast read write
• speed.
• Low power
• High density
• Fast read write
• speed.
• Fast read write
• speed.
• Low power
• High density
• Non Volatile

• Disadvantage
• Volatile
• Low density
• Volatile
• High power
• None ??

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Comparison with DRAM SRAM

• In DRAM SRAM, a bit is represented as charge
  stored in
• capacitor.
• In MRAM, data is stored as magnetic alignment of
  electrons in
• a ferromagnetic material. Spin up represents
  0 and spin down
• represents 1.
• MRAM promises
• Density of DRAM
• Speed of SRAM
• Non-volatility like flash memory.
• Thats why its called universal memory.

256 K MRAM
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Journey of MRAM

• Problems encountered
• 1. The density of bits was low.
• 2. Cost of chips was high.
• Improved designs to overcome these problems
  would work
• only at liquid nitrogen temperature.
• An important breakthrough was made in the year
  2009.
• Scientists at the North Carolina State
  University discovered
• a semiconductor material Galium manganese
  nitride that
• can store retain spin orientation at room
  temperature.
• And research is still going on

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Thanks for your attention!!!
Any Queries ??