The 1996 paper published by John Slonczewski was updated in 2011 by Dr Daniel Worledge and colleagues, who outlined a technique to produce MRAM with manufacturing line widths of less than 20nm. The approach – called perpendicular magnetic anisotropy (PMA) – was seen as a critical discovery because it would enable spin torque MRAM to scale to much higher densities.
What that team did was to develop magnetic materials that allowed the magnet to point perpendicularly, instead of in the plane. However, Dr Worledge and his colleagues believed they could scale even further, resulting in even denser MRAM.
Now, Dr Worledge and colleagues, along with partners at Samsung, have published a paper demonstrating how MRAM cells with diameters as small as 11nm can switch in 10ns using a current of 7.5µA.
“With PMA, we are capable of delivering good STT-MRAM performance down to write-error-rate of 7×10-10 with 10ns pulses and switching currents of 7.5µA. This could never be done with in-plane magnetised devices — they just don’t scale.
“While more research needs to be done, this should give the industry the confidence it needs to move forward. The time for Spin Torque MRAM is now.”
