Magnetics Business & Technology - March/April 2022 - 12

FEATURE ARTICLE
New Developments in Spintronics Technology Come at Blistering Pace
of a fixed magnetic layer, a thin dielectric tunnel barrier and a free
magnetic layer. When a bias is applied to the MTJ, electrons that
are spin polarized by the magnetic layers traverse the dielectric
barrier through a process known as tunneling.
Everspin's newest MRAM technology use spin torque transfer,
which is the manipulation of the spin of electrons with a polarizing
current, to establish the desired magnetic state of the free layer to
program, or write, the bits in the memory array. It provides a significant
reduction in switching energy compared to Toggle MRAM,
and is highly scalable, enabling higher density memory products.
In a recent case study, Cobham validates the versatility and performance
for space application of Toggle MRAM jointly developed
with Everspin. Cobham provides the aerospace industry with radiation
hardened, highly reliable non-volatile memory that is designed
for the rigors of space endurance and greater than 20-year
retention across a -40° C to +105° C temperature range.
" Everspin's MRAM technology has proven itself in the market with
a production track record of high performance and endurance,
providing superior non-volatile data retention to handle a variety of
space mission-critical memory workloads, " said David Meyouhas,
director of standard product marketing, space and semiconductor
solutions, Cobham AES.
Its third generation of MRAM technology, it uses a perpendicular
magnetic tunnel junction. The company has developed materials
and stack designs with high perpendicular magnetic anisotropy
which provides long data retention, small cell size, greater density,
high endurance and low power. The 1Gb is the newest generation
and additional products are planned which will utilize high speed
serial interfaces for a wide range of embedded applications.
World's smallest high-performance magnetic tunnel junctions
At Tohoku University, researchers led by current president Hideo
Ohno report they have developed the world's smallest high-performance
magnetic tunnel junctions, measuring only 2.3 nanometers.
The development of non-volatile spintronics memory
(STT-MRAM) helps reduce the increasing power consumption in
semiconductor device scaling. Crucial to integrating it in advanced
integrated circuits is scaling magnetic tunnel junction, a core component,
while improving its performance in data retention and
write operation.
Toggle MRAM from Everspin
Toggle MRAM uses a 1 transistor, 1 MTJ cell to provide a simple,
high-density memory. Everspin uses a patented Toggle cell design
that delivers high reliability. Data are always non-volatile for
20-years at temperature. During a read, the pass transistor is activated
and data is read by comparing the resistance of the cell to a
reference device. During writes, the magnetic field from Write Line
1 and Write Line 2 writes the cell at the intersection of the two lines
but does not disturb other cells on either line. Everspin MRAM
products employ a one transistor, one magnetic tunnel junction
(MTJ) memory cell for the storage element. The MTJ is composed
© Butsurin Jinnai and Shunsuke Fukami
Building on their earlier work, the group employed a new structure,
depicted on the right, that uses magnetostatically coupled
multilayered ferromagnet and exhibited high data retention. " The
performance proves the developed MTJs' capability to work with
the future-generation advanced integrated circuits, " said Butsurin
Jinnai, first author of the study, " High-Performance Shape-Anisotropy
Magnetic Tunnel Junctions down to 2.3 nm " , presented at the
IEEE International Electron Devices Meeting.
Spin-transfer Torque MRAM Technology
12 Magnetics Business & Technology * March/April 2022
Breaking speed record for switching magnetization
In France, researchers led by CNRS developed a new technique
that can switch magnetization in only six picoseconds, which is
almost 100-times faster than current state-of-the-art spintronics
- and is also highly efficient. A picosecond is one-trillionth of a
second.
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Magnetics Business & Technology - March/April 2022

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