This document outlines the evolution of spintronics and its applications. It discusses how spintronics was developed to address limitations of Moore's Law, including heat generation and quantum effects at small scales. Giant magnetoresistance was discovered, allowing development of technologies like hard disk drives, magnetic tunnel junctions, and magnetic random access memory. These applications leverage the spin-dependent scattering of electrons in ferromagnetic materials to provide non-volatile data storage and sensing capabilities with advantages in speed, cost and capacity compared to traditional electronics. Spintronics continues to be explored for three-dimensional memory architectures like race track memory.

1. Hardik Patel
-3146504
Embedded System Design
SVE, NIT Kurukshetra
SPINTRONICS
….. a new era in electronics

2. OUTLINE :
• Need ??
• Magnetics and Storage
• Evolution
• GMR
• Hard Disk Drive
• MTJ
• MRAM
• Race Track Memory
• Logical Comparison
• Conclusion

3. • NEED OF SPINTRONICS ???
 Failures of MOORE’s Law….
Law states that “ Transistor counts doubles Every 18 to 24 months”
so because of high packing density increasing we are facing to many problems.
some of the major problems are….
1) SCORCHING HEAT generation making the circuit inoperable
2) QUANTOM EFFECT comes in to play at nanoscale dimension
So, the size of the transistor and other component can’t be reduced further.
As a result other quantum mechanics property of electron ‘SPIN’ is taken in
to consideration. i.e nothing but….
“SPIN + ELECTRONICS = SPINTRONICS”

4. • MAGNETIcs & Storage

5. • EVOLUTION
CURRENT IN A METALIC CONDUCTOR
In a non magnetic conductor , electron scatters the same amount regardless of spin as a
current flow.
How much they scatters determines the resistance of device.

6. CURRENT IN A FERROMAGNETIC CONDUCTOR
In a ferromagnetic conductor , however , electrons scatters differently depending on
whether they are spin up or spin down.
In this Case , spin up electrons are scatters strongly while the spin down electrons are
scattered only weakly.

7. SPIN-DEPENDENT SCATTERING
If a non-magnetic conductor is sandwiched between two oppositely magnetized
ferromagnetic layers, a number of electrons will scatter strongly when they try to
cross between the layer.
This gives high resistance.

8. SPIN-DEPENDENT SCATTERING
If the ferromagnetic layers are magnetized in same direction , far fewer electrons are
strongly scattered and more current flows.
This is measured as a low resistance.
Useful foe sensing magnetic fields or as a magnetic memory element
 SPIN-VALVE magnetic sensor

9. • GIANT MAGNETORESISTANCE (gmr)
* Parkin et.al.proc. IEEE (2003)

10. • HARD DISK DRIVE
READING : read head senses the stray field of the domain wall
WRITING : write head writes the bit by magnetic field

11. HARD DISK DRIVE EVOLUTION OVER 50 YEARS
* Photo Of HDD at IBM Museum

12. HARD DISK DRIVE EVOLUTION OVER 50 YEARS
* Photo Of HDD at IBM Museum

13. • Spintronics  Spin Valve Sensor  Magnetic Tunnel Junction
-> Major impact on hard disk drive storage
-> enabled >x1000 increase in storage capacity since 1998
-> make possible miniaturization of hard disk drives
 cell phones , PDA , MPEG players
-> make possible access to all the information
• Spintronics  Magnetic Tunnel Junction
 Magnetic Random Access Memory
 Spin Torque switching using spin currents

14. • MAGNETIC TUNNEL JUNCTION
 In a ferromagnet current is spin filtered
Magnetic Tunnel Junctions
(MTJs) are attractive for use
in device because they are
Inherently higher resistance,
Which is usefull in very small
sacle Solid State circuitry.
Moments Parallel
 High Current
Moments Anti-parallel
 low Current

15. USEFULL MAGNETIC TUNNEL JUNCTIONS (MTJ) !
- Magnetron or ion beam Sputtered at ambient
temp. on amorphous SiO2
- Artificial antiferromagnetic reference layer
needed!

16. • MTj electron micrograph
By sandwiching amorphous structure between ferromagnetic layer we can
get this type of observation through electron microscope.
*Parkin ,US Patent filed (2003)
*Published Nature Materials (2004)

17. • MTj electron micrograph
By sandwiching amorphous structure between ferromagnetic layer we can
get this type of observation through electron microscope.
*Parkin ,US Patent filed (2003)
*Published Nature Materials (2004)

18. •MAGNETORESISTIVE MATERIAL EVOLUTION
Huge room temp. TMR values in MTJs useful for memories and sensing application.
[Parkin et al. nature mater.(2004)] ~220% in 2001-2002:400-800% today
*MgO tunnel barriers and method of formation , S.S.P. Parkin, filed August 22,2003

19. • IBM LABORATORY MANUFACTURING

20. •Magnetic random access memory (mram)
By using MTJ at cross section of wires we can make the non-volatile memory.
Cross-Point Array of MTJ
*Parkin et al. J . Appl. Phys.(1999) ;Proc. IEEE(2003)

21. Cross-Point Array of MTJ
*Parkin et al. J . Appl. Phys.(1999) ;Proc. IEEE(2003)
• MRAM READING

22. Cross-Point Array of MTJ
*Parkin et al. J . Appl. Phys.(1999) ;Proc. IEEE(2003)
•MRAM WRITING

23. Cross-Point Array of MTJ
*Parkin et al. J . Appl. Phys.(1999) ;Proc. IEEE(2003)
•MRAM WRITING

24. •RACE TRACK MEMORY
*Parkin , US patents 6,834,005 (2004)

25. •THREE DIMENSIONAL STORAGE MEMORY
•Capacity Of HDD • Capacity Of FLASH
Since it has a three dimension , It is similar to real estate on silicon!!!!

26. •LOGICAL COMPARISION

27. • ADVANTAGES
• Non Volatile
•Doesn’t require specific materials
•Speed
•Cost
• Advantage of Both electronics and Magnetics

28. • COnClUSION :
As said in the starting itself that it is a new era in electronics . That we can conclude
From its advantages also.
By using all electronic and magnetic properties of charge this field open the door for
many new invention and possibilities in future.

29. •REFERENCES

30. THANK YOU!!!