by josh perry, editor
[email protected]

magnetic tunnel junctions (mtj) are the key to spin-transfer torque-magnetoresistive random access memory (stt-mram), which is expected to be commercialized this year and could replace semiconductor-based memories because of its ability to work without a power supply, and a team from tohoku university (sendai, japan) has taken the technology a step further.

researchers created mtj that were smaller than 10 nanometers. (tohoku university)

according to a report from the university, scientists used a shape anisotropy that had not been utilized before to develop ultra-small mtj that are smaller than 10 nanometers. this could produce more efficient stt-mram with double the retention and switching properties.

the article explained, “the ‘shape-anisotropy’ mtj has a pillar-shaped magnetic layer, by which the film's normal direction becomes a magnetic easy axis due to the ‘shape anisotropy’. this is in contrast to the ‘interfacial-anisotropy’ mtjs, which were achieved by reducing the thickness of the magnetic layer. the smallest diameter of mtj studied was 3.8 nm, which is an unprecedented scale based on previous research endeavors.”

experiments showed high thermal stability, which indicated high retention properties. the researchers believe that this technology could work with future semiconductors. a single-digit-nanometer mjt corresponds to 100 gb capacity, 100 times larger than current memory technology.

the research was recently published in nature communications. the abstract stated:

“nanoscale magnetic tunnel junctions play a pivotal role in magnetoresistive random access memories. successful implementation depends on a simultaneous achievement of low switching current for the magnetization switching by spin transfer torque and high thermal stability, along with a continuous reduction of junction size.

“perpendicular easy-axis cofeb/mgo stacks possessing interfacial anisotropy have paved the way down to 20-nm scale, below which a new approach needs to be explored. here we show magnetic tunnel junctions that satisfy the requirements at ultrafine scale by revisiting shape anisotropy, which is a classical part of magnetic anisotropy but has not been fully utilized in the current perpendicular systems.

“magnetization switching solely driven by current is achieved for junctions smaller than 10 nm where sufficient thermal stability is provided by shape anisotropy without adopting new material systems.

“this work is expected to push forward the development of magnetic tunnel junctions toward single-digit nm-scale nano-magnetics/spintronics.”