1. MRAM prototypes of many MegaByte capacity
has already been built, and they are poised to
enter the production lines.
But new concepts of even much faster MRAMs are
still emerging. One such idea is to use the so-called
“Spin Torque Transfer” (STT) effect for toggling
between the 0 and the 1 states of a memory cell.
The STT effect was predicted theoretically in 1996
independently by J. Slonczewski and L. Berger.

2. (J. Slonczewski, JMMM 1996, L. Berger, PR B 1996)
Spin transfer
(J. Slonczewski, JMMM 1996, L. Berger, PR B 1996) S
 Torque on S  Mx(MxM0)
Ex:Cobalt/Copper/ Cobalt
The transverse component of the spin current is absorbed and transferred to the total spin of the layer
 j M x (M x M0)

3. Web link to the
Entire paper:
Click here

4. The 01 and 10 switching of a STT memory cell can be done
by sending short current pulses through the cell in opposite
directions:
(for detailed explanation, read the text in the next slide)

6. Novel effects and futuristic ideas:
Spin Hall Effect: “Pure” spin current:
Ordinary current:
transport of charge
“Pure spin current”:
transport of spin
Pure spin current is indeed a fascinating idea:
No charge transfer – problems with inductance
or capacitance do not exist any more… Zero
power dissipation! But how such currents can
be “generated”? The Spin Hall Effect may be
too weak a source for practical applications,
but at least it may be used for testing the idea…

7. Link to the entire article: click