MRAM research or technical information

Superlattice and half-metallic magnets used to developed SS-MRAM, an ultra-high performance MRAM device

Researchers from the National Taiwan University developed an ultra-high performance MTJ, using a superlattice barrier and half-metallic magnets. The so-called superlattice-MTJ can be the basis of a new class of STT-MRAM (which the researcher call SS-MRAM) that achieves ultra-low power RA and write operations, high writing speed and unlimited endurance.

Geometric structure of a three-cell superlattice MTJ (National Taiwan University)

SS-MRAM adopts a superlattice barrier that replaces the MgO layer used in common STT-MRAM. The MgO layer is unstable and also suffers from a very large RA which results in high power consumption for writing operations. The superlattice has higher spin polarization than MgO and so the SS-MARM can provides not only ultra-high MR ratio but also ultra-low RA for high-speed and low power writing.

NTHU researchers discover that a thin film of platinum can enable faster and more efficient MRAM

A team of researchers from the National Tsing Hua University (NTHU) in Taiwan have discovered that by adding a layer of platinum only a few nanometers thick, one can switch the pinned magnetic moments at MRAM cells at will. This was never achieved before, and can lead to faster and more efficient MRAM devices.

The platinum layer is placed between the two layers of the MRAM device - the upper layer, a freely flipping magnet used for data computation and the bottom layer that consists of a fixed magnet, responsible for data storage. Due to spin-orbit interactions, the electric current drives the collective motion of electron spins first. The spin current then switches the pinned magnetic moment effectively and precisely.

New four-state MTJ architecture may lead to multi-level MRAM

An international team of researchers led by Israel's Bar Ilan University have developed a new type of MTJ that has four resistance states. The researchers also demonstrated how it is possible to switch between these four different states using spin currents.

The four-state design uses a structure that is in the form of two crossing ellipses instead of one of the standard magnetic layers of the MTJ. Such a design could be used to create multi-level MRAM which stores data more densely compared to current MRAM memories which only have two states in each MTJ.

Researchers add YSZ layers to MRAM devices to increase efficiency and speed

Researchers from the Korea Institute of Science and Technology (KIST) have managed to drastically incraese the speed of MRAM devices while reducing the power consumption by adding a layer of yttria-stabilized zirconia (YSZ) to MRAM devices.

KIST ultra-low power and high-speed MRAM prototype

The YSZ layer, which has high ion conductivity helps inject hydrogen ions into the MRAM cell. This resulted in an increase in the speed of the spin alignment direction changes 100-fold.

Successful MRAM Production Requires Good Magnetic Test Equipment

This is a sponsored post by Integral Solutions Int'l

MRAM is likely to be the most promising next-generation non-volatile memory technology today. Toggle MRAM and STT-MRAM are already entering the market, gaining market share in many applications. Next-generation MRAM technologies, such as SOT-MRAM could enable the replacement of even the fastest SRAM applications, with higher densities.

MRAM Manufacturing Process Flow (Coughlin)Source: Coughlin Associates, 2019

The MRAM production process has many stages, as device architecture is relatively complex, with a magnetic cell (frontplane) fabricated on top of a CMOS backplane. (use Figure 2 or Figure 3 from Coughlin). Measurement and characterization of devices are highly important, and the production of MRAM memories depend on measurement tools are are specialized for MRAM and STT-MRAM measurements.

New research may hold the key towards antiferromagnetic MRAM

Researchers from the University of Arizona discovered that in common Magnetic Tunnel Junctions (MTJ), there's a thin (2D) layer of Iron Oxide. This layer was found to act as a contaminant which lowers the performance achieved by MTJs, but it may also hold the key to use antiferromagnetism in MRAM devices.

Magnetic Tunnel Junction schematic (UArizona)

The researchers discovered that the layer behaves as a so-called antiferromagnet at extremely cold temperatures (below -245 degrees Celsius). Antiferromagnets are promising as these can be manipulated at Terahertz frequencies, about 1,000 times faster than existing, silicon-based technology. This is the first research that shows how Antiferromagnets can be controlled as part of MTJs and in the future may pave the way for its adoption in MRAM devices.

Researchers show how antiferromagnetic STT-MRAM technology can enable higher-density and lower energy memory

Researchers from Northwestern University suggest building STT-MRAM devices from antiferromagnetic materials - as opposed to the currently-used ferromagnetic ones. The researchers say that these materials will enable higher-density devices that feature high speed writing with low currents.

Antiferromagnetic materials are magnetically ordered at the microscopic scale, but not at the macroscopic scale. This means that there is no magnetic force between adjacent bits in MRAM cells built from these materials - which means you can pack them very close together.

Researchers demonstrate that chalcogenide materials can be highly suitable for SOT-MRAM

Researchers from National Taiwan University demonstrate that chalcogenide material BiTe with non-epitaxial structure can give rise to a giant spin Hall ratio and SOT efficiency (~ 200%) without obvious evidence of topologically-protected surface state (TSS).

BiTe material system for SOT-MRAM schema (NUS)

The researchers explain that a clear thickness-dependent increase of the SOT efficiency indicates that the origin of this effect is from the bulk spin-orbit interaction of such materials system. Efficient current-induced switching through SOT is also demonstrated with a low zero-thermal critical switching current density (~ 6×105 A/cm2).

New USMR MRAM structure promises extremly simple design

Researchers from Tokyo's Institute of Technology (Tokyo Tech) developed a new MRAM cell structure (called USMR MRAM) that features a very simple structure with only two layers - which could hopefully enable lower-cost MRAM devices.

USMR MRAM cell structure image

The new design uses a combination of a topological insulator with a ferromagnetic semiconductor which enables a giant unidirectional spin Hall magnetoresistance (USMR).