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MRAM is a type of non-volatile random access memory that uses magnetic storage and magnetoresistance to read stored data. It has advantages over other RAM types like being non-volatile, having infinite write cycling without wear, fast write speeds, low write energy usage, and non-destructive reads. MRAM uses giant magnetoresistance or tunnel magnetoresistance to change electrical resistance depending on the magnetic field, allowing a sense current to detect stored bits during reads. Development of MRAM has increased its capacity and speed over time.

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193 views12 pages

PPT

MRAM is a type of non-volatile random access memory that uses magnetic storage and magnetoresistance to read stored data. It has advantages over other RAM types like being non-volatile, having infinite write cycling without wear, fast write speeds, low write energy usage, and non-destructive reads. MRAM uses giant magnetoresistance or tunnel magnetoresistance to change electrical resistance depending on the magnetic field, allowing a sense current to detect stored bits during reads. Development of MRAM has increased its capacity and speed over time.

Uploaded by

ajaydev2224
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
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MRAM

(Magnetoresistance Random Access Memory)

NAME- ATUL KUMAR JADON CLASS- ECE

What is MRAM?
MRAM is a nonvolatile random access memory which uses magnetic storage and magnetoresistance (MR) to read the stored data.

Magnetoresistive material is a resistor made of common ferromagnetic material which will change in resistance in the presence of a magnetic field.

The general attributes of MRAM are:


Nonvolatility Infinite write cycling without wearout Fast write (few nanoseconds for advanced modes) Low write energy Nondestructive read.

MRAM: Writing process


Transistor is OFF
When current is passed through the write lines, an induced magnetic field is created at the junction, which alters the polarity of the free layer.

MRAM: Reading process


Transistor is ON
Measuring of electrical resistance of a small sense current from a supply line through the cell to the ground.

Magnetoresistance
This is the observable change in electrical resistivity when a magnetic field is present. Two of the most useful types of Magnetoresistance are;

Giant Magnetoresistance

Tunnel Magnetoresistance

Giant Magnetoresistance
GMR can occur between two adjacent ferromagnetic
layers separated by a spacer.
Electrons with their spins aligned with the ferromagnetic

moment are less likely to scatter which leads to lower resistance.


High resistivity = anti parallel alignment Low resistivity = parallel alignment

Tunnel Magnetoresistance
Spin of electrons is conserved in the tunneling process. Tunneling of up- and downspin electrons are two independent processes conductance occurs in the two independent spin channels. Electrons originating from one spin state of the first ferromagnetic film are accepted by unfilled states of the same spin of the second film.

Other RAM Technologies


DRAM
Each bit of data is stored in a separate capacitor within an integrated circuit

Characteristics
The highest density RAM currently available The least expensive one Moderately fast Volatile

Other RAM Technologies


SRAM
Each bit is stored on four transistors that form two crosscoupled inverters

Characteristics Volatile
Expensive Fast Low power consumption Less dense than DRAM

MRAM Status
2003 - A 128 kbit MRAM chip was introduced, manufactured with a 180 nm lithographic process 2004 - Infineon unveiled a 16-Mbit prototype, manufactured with a 180 nm lithographic process 2005 - Sony announced the first lab-produced spin-torque-transfer MRAM 2007 - Tohoku University and Hitachi developed a prototype 2 Mbit Non-Volatile RAM Chip employing spin-transfer torque switching 2008 - Scientists in Germany have developed next-generation MRAM that is said to operate with write cycles under 1 ns. 2009 - Hitachi and Tohoku University demonstrated a 32-Mbit spintransfer torque RAM (SPRAM)

REFERENCES
www.mram-info.com/ www.nve-spintronics.com/mram-operation.php en.wikipedia.org/wiki/Magnetoresistive_randomaccess_memory www.sciencedaily.com/articles/m/mram.htm

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