Spintronics utilizes the spin property of electrons to carry information. It offers advantages over traditional electronics like lower power consumption and greater density. Key developments include the giant magnetoresistance effect, spin transistors, and magnetic random access memory (MRAM). Continued research aims to better inject, manipulate, and detect electron spin in semiconductors for applications in memory and logic devices.

1. Spintronics
“A Spin to Remember”
Submitted To:- Presented By:-
Er. Pieush Vyas Abhishek Shringi
(Associate Professor) 08/33/106
(Unit In charge EC) VIII Sem ECE

2. Outline
• Spintronics basics
• The giant magneto resistance
• Applications of GMR
• Spin devices
• Injections & detection of spin
• The MRAM
• Recent trends

3. What is Spintronics?
• Utilizes the bizarre
property of spin of
electron.
• Intrinsic angular
momentum is spin.
• Two arbitrary
orientations, and its
magnitudes are ± ħ / 2
(ħ is Plank constant).
• Directional and
coherent motion of
electron spin circulates
a spin current, which
will carry or transport
information and control
quantum spin in an
spintronic device.

4. Why Spintronics?
• Moore’s Law:
No. of Transistor doubles in every 18 months.
•Complexity:
Complex Chip Design & Power Loss.
• Motivation:
Spintronics-Information is carried not by electron
charge but by it’s spin.

5. Moore’s law

6. Combining the best of both worlds
Ferro magnets Semiconductors
• Stable Memory • Bandgap engineering
• Fast switching • Carrier density & type
• High ordering temp • Electrical gating
• Long spin lifetime
• Spin transport
• Technological base
• Technological base (Electronics)
(magnetic recordings)
Can we develop spin based How to create control propagate
transistors , switches and logic spin information in semiconductor
circuits? structures?

7. The Giant Magneto Resistance
• A Nano scale phenomena .
• Giant refers to giant change in resistance due to
current.
• It is a quantum mechanical magneto resistance
effect observed in thin-film structures composed of
alternating ferromagnetic and non-magnetic
layers.

10. Magnetic tunneling junction
• Like GMR but better.
• More sensitive
• Multilayer junction
filter
• Quantum
mechanical principle
• Tunneling effect
• 2 layers of magnetic
metal, separated by
an ultrathin layer of
insulator, about 1
nm.

12. Spin transistor
• Supriyo Datta and Biswajit Das Transistor

13. Spin injection into silicon
• Injection

14. Spin manipulation
• Hanle effect :- Suppression of spin accumulation
Ferro magnet
Oxide
Silicon
B
Spin

15. Magnetic field along the spin
• Hanle curve for a) Ge , b) Si

16. Detection of spin polarization in
silicon
Tunnel barrier
Spin accumulation
e-
u
Ferro magnet Al2O3 n type Silicon
Tunnel resistance in proportional to u
I =G *(V- u/2)
I =G *(V+ u/2)

17. MRAM
Magneto resistive RAM
Reading process
• Measurement of the
bit cell resistance by
applying a current in
the ‘bit line’
• Comparison with a
reference value mid-
way between the bit
high and low
resistance values

18. MRAM
Magneto resistive RAM
Writing process
• Currents applied in both
lines : 2 magnetic fields
• Both fields are
necessary to reverse
the free layer
magnetization
• When currents are
removed : Same
configuration

19. MRAM
Magneto resistive RAM
Array structure of MRAM
• Reading: transistor of
the selected bit cell
turned ‘on’ + current
applied in the bit line
• Writing: transistor of the
selected bit cell turned
‘off’ + currents applied
in the bit and word lines
• Need of 2 magnetic
fields for writing

20. MRAM vs …..

21. MRAM
Magneto resistive RAM
• MTJ test structures developed at SPINTEC: the die area with 1x5 μm
• 0.2 μm width isolated MTJ element after etch

22. Advantages of 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.

23. Conclusion
• Spin property of electrons are yet to mastered.
• Researcher and scientist are taking keen interest.
• Universities and electronic industries collaborating .
• Span of last two decade major milestones.
• It holds vast opportunities for physics , material &
device engineering & technology
• Last year PTB, Germany, have achieved a (2GBit/s)
write cycle
• Potential of the field is colossal and
continuous development is required.