1. GEETA INSTITUTE OF MANAGEMENT AND
TECHNOLOGY
Presentation
On
Submitted To: Presented By :
ER. ANKUR GUPTA AMIT VATS
R. No : 3608267
Final B. Tech. (ECE)

2. 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.

3. Why We Need Spintronics !
Failure of Moore’s Law :
 Moore’s 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. SRAM VS DRAM VS MRAM
Advantage Disadvantage
SRAM • Fast read & write • Volatile
speed. • Low density
• Low power
• High density • Volatile
DRAM
• Fast read &write • High power
speed.
• Fast read &write
MRAM • None ??
speed.
• Low power
• High density
• Non Volatile

11. 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.
 That’s why its called universal memory.
256 K MRAM

12. 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…

13. Thanks for your attention…!!!
Any Queries ??