Its about electron spinning on spin valve sensor also GMR head

1. ALAGAPPA UNIVERSITY
(A State University Accredited with “A+” Grade by NAAC (CGPA: 3.64) in the Third
Cycle and Graded as Category-I University by MHRD -UGC)
KARAIKUDI – 630 003

2. QUANTUM MECHANICS
• It requires of 4 quantum numbers to describe to the distribution and behavior of
electrons in atoms.
• They derive from the Equation of Schrödinger for the hydrogen atom.
• The Quantum Numbers are : n l m s

3. QUANTUM NUMBER

4. SPINTRONICS
• Spintronics or spin electronics is the study of the role that is played by the spin of
an electron in the solid state physics and other devices that exploit spin properties.
• Spintronics helped in creating a prototype device which used in industry as a read
head and a memory-storage cell is the giant-magneto resistance (GMR) sandwich
structure which consists of alternating ferromagnetic and nonmagnetic metal
layers.
• Depending on the relative orientation of the magnetizations in the magnetic
layers, the device resistance changes from small (parallel magnetizations) to large
(antiparallel magnetizations)

5. ELECTRON SPIN DIRECTION
This change in resistance (also
called magnetoresistance) is used to sense
changes in magnetic fields Electron spin
can be identified as a magnetic field having
one of two positions, known as up and
down.

6. COMBINING THE BEST OF BOTH
WORLDS
Ferro magnets
• Stable Memory
• Fast switching
• High ordering temp
• Spin transport
• Technological base (magnetic
recordings)
Semiconductors
• Bandgap engineering
• Carrier density & type
• Electrical gating
• Long spin lifetime
• Technological base (Electronics)

7. GIANT MAGNETO RESISTANCE
• Giant magnetoresistance (GMR) is a quantum magneto resitance effect observed
in thin film structures composed of alternating ferromagnetic and non magnetic
layers.
• It is also a way to control the electrical
resistance at the nano scale using magnetic
field.

8. BASIC THEORY
• Electron spin & atom magnetic moments.
• On parallel- weak scattering
• On antiparallel-strong scattering
• More scattering= higher electrical
reisitance

9. VARIOUS STRUCTURES IN WHICH GMR
CAN BE OBSERVED
• magnetic multilayer
• pseudo spin valve
• spin valve
• granular thin film

10. SPIN-VALVE SENSOR

11. APPLICATIONS OF SPINTRONICS
• Spintronic devices are used in the field of mass-storage devices. It is used to
compress massive amounts of data into a small area, as an instance, approximately
one trillion bits per square inch (1.5 Gbit/mm²) or roughly 1 TB data can be stored
on a single sided 3.5″ diameter disc.
• Spintronics is also used in the medical field to detect cancer.
• Spintronic technology in general holds promises for digital electronics. It has been
tested in mass-storage components namely hard drives.

12. REFERENCE
• https://arxiv.org/ftp/arxiv/papers/1412/1412.7691.pdf
• https://byjus.com/physics/spintronics/
• https://www.researchgate.net/figure/Schematic-of-a-simple-spin-valve-read-
sensor-stack-and-a-spin-valve-with-a-synthetic_fig2_263715562
• https://www.daviddarling.info/encyclopedia/Q/quantum_number.html
• https://www.qsstudy.com/physics/electron-spin-experiment