SPINTRONICS Submitted by: K Chinmay Kumar N/09/09 0901204081 Applied Electronics And Instrumentation Engg Roland Institute Of Technology

OUTLINE WHAT IS SPINTRONICS ?? WHY WE NEED SPINTRONICS ??? PRINCIPLE & ITS ADVANTAGES FABRICATION PROCESS SRAM Vs DRAM Vs MRAM ELECTRONICS Vs SPINTRONICS APPLICATIONS CONCLUSION

WHAT IS SPINTRONICS ?? Spintronics is a combination of two words (spin & electronics) Spintronics is a blend of electronics with spin. It refers to the study of the role played by the electron spin in solid state physics It enhances functionality, high speed and reduced power consumption.

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 the circuit inoperable. 2. Also Quantum effects come into play at nanoscale dimensions.

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. The frequency and direction of rotation depends on the strength of magnetic field and characteristics of the material.

ADVANTAGES 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. Common metals such as Fe, Al, Ag etc... can be used.

FABRICATION Spintronics devices involves two different approaches for designing & manufacturing. Giant-magneto resistance, GMR based technology Tunnel-magneto resistance, TMR based technology

GAINT MAGNETORESISTANCE(GMR) The basic GMR device consists of a layer of non -magnetic metal between 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.

When the two magnetization vectors of the ferromagnetic layers are aligned, the electrical resistance will be lower than if the ferromagnetic layers are anti-aligned. Data on hard disc drives is stored as a directed magnetic field in particles. Two variants of GMR have been applied in devices: 1. Current-in-Plane(CIP): In this type of device the electric current flows parallel to the layers. It is most commonly used in magnetic read heads. 2. Current-Perpendicular-to-Plane (CPP): In this type of device the electric current flows in a direction perpendicular to the layers. It is the basis for Tunnel Magneto Resistance (TMR).

TUNNEL MAGNETORESISTANCE Tunneling Magneto Resistance (TMR) is a device where two ferromagnetic layers are separated by a thin (about 1nm) insulator layer and the electric current tunnels through or flows in a direction perpendicular to the layers. 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 .

Magnetoresistive Random Access Memory (MRAM) Another recent breakthrough product in Spintronics is Magneto Resistive RAM (MRAM), which uses electron spin to store information. MRAM is a non-volatile computer memory (NVRAM) technology, which has been under development since the 1990s.

Conventional RAM chip technologies store data as electric charge or current flows. In MRAM tunnel junctions are used to store the information, typically ”0” for aligned state and “1” for anti –aligned state.

SRAM VS DRAM VS MRAM ADVANTAGE DISADVANTAGE SRAM Fast read & write speed. Low power Volatile Low density DRAM High density Fast read &write High power MRAM speed, high density Non Volatile Not discoverable till date

ELECTRONICS vs SPINTRONICS One of the main advantage of spintronics over electronics is the magnets tend to stay magnetize which is sparking in the industry an interest for replacing computer’s semiconductor based components with magnetic ones, starting with the RAM. With an all-magnetic RAM, it is now possible to have a computer that retains all the information put into it. Most importantly, there will be no ‘boot-up’ waiting period when power is turned on.

ELECTRONICS vs SPINTRONICS Another advantage includes Non-volatility Spins don’t change when power is turned off. The peculiar nature of spin and quantum theory describes it point to other wonderful possibility like various logic gates whose function can be changed billion times per second.

APPLICATIONS GMR sensors find a wide range of applications: Fast and accurate position and motion sensing of mechanical components in precision engineering and robotics. Missile Guidance Position and motion sensing in computer video games. Automotive sensors for fuel handling system, speed control and navigation etc…

CONCLUSION With lack of dissipation, spintronics may be the best mechanism for creating ever-smaller devices. The potential market is enormous. In maybe a 10-year timeframe, spintronics will be on par with electronics. That's why there's a huge race going on around the world in exploring Spintronics

REFERENCE WEBSITES:- http://hyperphysics.phy-astr.gsu.edu/hbase/spin.html http://prb.aps.org/abstract/PRB/spin.orientation/i4/e045317 http://dictionary.reference.com/browse/frequency/spin BOOKS REFERRED:- Zutic, J. Fabian, and S. Das Sarma, "Spintronics: Fundamentals and Applications," Rev. Mod. Phys. 76, 323 (2004). U. Hartmann, ed., Magnetic Multilayers and Giant Magnetoresistance: Fundamentals and Industrial Applications (Springer, 2000).

Thankyou

Any Queries???....