WELCOME

RACETRACK MEMORY

PRESENTED BY

RAJEEB R VRoll No: 12S7 ECCollege of Engg. Attingal

GUIDE

SENTHIL NIVAS

HISTORY OF STORAGE

MAGNETIC TAPE

FLOPPY DISK OPTICAL DISK

HARD DISK DRIVE

SOLID STATE DRIVE

WHAT’S NEXT

RACETRACK MEMORY• Racetrack memory (or domain-wall memory (DWM)) is a non-

volatile memory device under development at IBM's Almaden Research Center.

• In early 2008, a 3-bit version was successfully demonstrated.• Racetrack memory, so named because the data "races" around

the wire "track“.• A U-shaped magnetic nanowire is embedded into a silicon chip. • Unlike conventional memory, which relies on electronic

charges to store data, Racetrack uses the spin of an electron.• The operation of racetrack memory is analogous to a solid-

state, non-volatile shift register.• Stores bits of information in the magnetization orientation of

regions in a U channel-shaped ferromagnetic structure.

WORKING PRINCIPLE

• Blue and red colored regions indicate domains of opposite magnetization

• BLUE- Binary 1

• RED- Binary 0• Pulsed current perpendicular to the

structure pushes domains into or away from reading/writing elements.

• WRITING- By moving the stray field from a neighboring domain wall into and out of range of the racetrack.

• READING- Using TMR

WRITING

READING

Pushing

domain walls

MAGNETIC DOMAIN• Each electron posses a magnetic moment due to the

spin of electrons • In unmagnetised state the magnetic moment have

different direction and the total magnetic moment cancels out.

• When a strong external magnetic field is applied the magnetic moment of each electrons lined up with respect to the external filed.

• In ferromagnetic materials even after the removal of external magnetic field in each domain, all of the atomic dipoles are coupled together in a preferential direction

DOMAIN

WRITING INFORMATION INTO THE RACETRACK

• Using magnetic domain wall injector• Red and Blue colour regions indicates

domain of opposite mangnetisation.• In domain wall injector current flows

in one direction for writing 0 and in opposite direction for writing bit 1

Writing Head

TUNNEL MAGNETORESISTANCE(TMR)• Tunnel magnetoresistance (TMR) is a

magnetoresistive effect that occurs in a magnetic tunnel junction (MTJ), which is a component consisting of two ferromagnets separated by a thin insulator.

• If the insulating layer is thin enough (typically a few nanometers), electrons can tunnel from one ferromagnet into the other.

• The direction of the two magnetizations of the ferromagnetic films can be switched individually by an external magnetic field.

• Parallel-Low resistance• Antiparallel-High resistance

READING INFORMATION FROM RACETRACK• Using Tunnel Magnetoresistance(TMR)• Resistance change for parallel and antiparallel magnetisation

between two plates • By measuring the resistance change we can determine whether it

is bit 0 or 1

SPIN POLARIZED CURRENT• As well as mass and charge, an electron has

another intrinsic property, i.e. spin angular momentum.

• Electron spin can only point to up or down along a magnetic field

Unpolarised

electrons

Normal Metal

Ferromagnetic Material

Spin UP e

Spin down e

Spin UP e

Spin down e

Equal Scattering

Unequal Scattering

• Spin-up electrons may encounter less scattering.• So the conductivity due to the majority spin

channel would be higher. • Then, a spin polarized current would emerge

from the ferromagnetic material

Shifting Domain Walls Down the Racetrack

• The most challenging part of the racetrack memory• It determines the speed, efficiency and accuracy• All the domain walls should move at equal velocity• Movement of the domain walls can be achieved by

sending spin-polarized current through the racetrack.

• The dynamics of moving domain walls along the racetrack and controlling the position of the domains to a high degree of accuracy is under heavy research

CONSTRUCTIONAL OVERVIEW• A U-shaped ferromagnetic nanowire is embedded

into a silicon chip. • Using a 3D array of nanowire storage density can

be increased• Unlike conventional memory, which relies on

electronic charges to store data, Racetrack uses the spin of an electron.

• The tiny magnets slides along the notched nanowires at speeds greater than 100 meters a second

• Offers a speed of 100 of gigabytes per second

3D racetrack array

MATERIAL SELECTION

Material selection for the ferromagnetic racetrack material plays a large role in determining the dynamics of domain wall motion creation and movement.

Two type1. Hard – ability to manipulate domain walls and its width eg: Iron, cobalt2. Soft - eg: Crystalline cobalt iron(CoFe)

Ferromagnetic nanowire

THRESHOLD CURRENT To effectively integrate magnetic racetrack memory with CMOS

ICs, it is important to make sure the current densities required to move domain walls are sufficiently attainable.

In addition, high current densities can cause Joule heating and result in domain wall instability.

Recent racetrack memory prototypes developed at IBM have included heat sinks to account for this.

The total current density will still need to exceed the critical current density

ADVANTAGES No mechanical movement compared to HDD so speed is high Low cost compared to SSD Provides more storage density than HDD Provides more reliability Can store data for long time Less power

FUTURE OUTLOOK

Will be the Universal Memory Racetrack memory is a promising technology for permanent

storage of data. Within 10 years IBM says that they can bring the product at the

market Racetrack memory will replace all the HDD’s SSD’s and flash

drive in the near future.

CONCLUSION

Magnetic racetrack memory is an exciting new technology that has many fundamental advantages over current RAM, HDDs, and SSDs.

Its non-volatility, high read/write speeds, and potential for scalable ultra dense memory make it an attractive type of memory.

It allow every consumer to carry data equivalent to a college library on small portable devices.

In 2006, data centers in the US, required 6.9 Gigawatts of power, and if we use racetrack memory for storage needs it will cut the power significantly.

Will become universal memory within next few years

THANK YOU

ANY QUERIES?