Spintronics Memory

New principle may open the door to spin memory devices

A research team, led by Dr. Kim Kyoung-Whan at the Center for Spintronics of the Korea Institute of Science and Technology (KIST), has proposed a new principle which could give a boost to spin memory devices.

Conventional memory devices are classified into volatile memories, such as RAM, that can read and write data quickly, and non-volatile memories, such as hard-disk, on which data are maintained even when the power is off. In recent years, related academic and industrial fields have been working to accelerate the development of next-generation memory that is fast and capable of maintaining data even when the power is off.

New material opens new opportunities for future spintronics-based magnetic memory devices

Researchers from Seoul National University, Pohang University of Science and Technology, Korea Atomic Energy Research Institute and the Center for Quantum Materials in Korea have designed a prototype of a non-volatile magnetic memory device entirely based on a nanometer-thin layered material, which can be tuned with a tiny current. This finding opens up a new window of opportunities for future energy-efficient magnetic memories based on spintronics.

The choice of magnetic material and device architecture depends on the fact that non-volatile memory technologies have to guarantee safe storage, but also reliable reading and writing access. Hard magnets are perfect for long-term memory storage, because they magnetize very strongly and are difficult to demagnetize. On the contrary, soft magnets are desirable for adding new information to the memory device, because their magnetization can be easily reversed during the writing process. Put simply, ideal magnetic materials can be kept at a hard magnetic state to ensure the stability of the stored information, but be soft on demand.

Researchers develop a spintronics memory that switches its magnetization in 6 picoseconds

An international group of researchers, led by the 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. The new technique is also highly efficient.

Picoseconds switching of magnetic materials, CNRS

The experimental design used to create the ultra-fast magnetization switching included an optical pump directed at the photoconductive switch, which converts the light into 6-picosecond electric pulses. The structure guides these pulses toward the magnet. When the pulses reach the magnet, they trigger the magnetization switching.

Researchers incorporate an antiferromagnetic layer in an MTJ for the first time

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.

Magnetic Tunnel Junction schematic (UArizona)

This Iron Oxide layer, however, can also be seen as a blessing - 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.

NUS researchers identify the semimetal MoTe2 as a promising spintronics material

Researchers from the National University of Singapore (NUS) have identified a promising spintronics candidate material - few-layer thin semimetal molybdenum ditelluride (MoTe2).

Planar Spin Hall Effect observed in MoTe2 (NUS)

Semimetals feature material properties that are between metals and semiconductors. The researchers found that an extremely thin (few-layers, almost 2D) MoTe2 features an intrinsic Spin Hall Effect (SHE).

Researchers develop a simple MRAM structure based on unidirectional spin hall magnetoresistance (USMR)

Researchers from the Tokyo Institute of Technology (Tokyo Tech) developed a new MRAM cell structure that relies on unidirectional spin Hall magnetoresistance (USMR). The new cell structure is reportedly very simple with only two layers which could lead to lower-cost MRAM devices.

USMR MRAM cell structure image

The spin Hall effect leads to the accumulation of electrons with a certain spin on the lateral sides of a material. By combining a topological insulator with a ferromagnetic semiconductor, the researchers managed to create a device with giant USMR.

Quantum Well structures can enhance the TMR of MTJs

Researchers from Japan's National Institute for Materials Science (NIMS) have managed to introduce a quantum well structure into a conventional magnetic tunnel junction (MTJ). The researchers say that the QW structure can enhance the tunneling magnetoresistance (TMR) ratio by spin-dependent resonant tunnel (SDRT) effect, with a value of 1.5 times comparing with no SDRT case, at room temperature.

Quantum Well structure introduced to MTJs (NIMS)

The researchers tell us that the key point of the QW formation is the band mismatch between Cr and Fe for majority band, and the mismatch-free Fe/MgAl2O4 interface. The finding is not just useful for enhancement of TMR ratio, it also provides a benefit that the TMR ratio could be kept almost constant in a wide bias voltage range of from -1V to 0.5V.

Optically-assisted MRAM could be a thousand time more efficient then current MRAM devices

Researchers from the Moscow Institute of Physics and Technology, in collaboration with researchers from Germany and the Netherlands have developed a new memory technology they call optically-assisted MRAM which is based on changing the spin state via THz pulses.

The researchers say that the new technique is extremely efficient (the power required to switch a "bit" will be a thousand times smaller compared to current MRAM devices) and fast.

Researchers announce a breakthrough in pinning domain wall propagation

Researchers from Sultan Qaboos University in Oman, Johannes Gutenberg-Universität Mainz in Germany and Nanyang Technological University in Singapore have experimentally demonstrated a breakthrough in one of the major problems blocking the adoption of magnetic domain wall memory.

When recording each fresh bit of information onto a racetrack, there is considerable uncertainty about where each magnetic domain starts and ends, and an incorrectly-written bit can easily lead to the corruption of bits. The team, led by Professor Rachid Sbiaa of Sultan Qaboos University, devised a method to overcome this difficulty by using a staggered nanowire (see figure below).

Researchers develop a 200Mhz spintronics-based microcontroller unit

Researchers from Japan's Tohoku University have developed a nonvolatile microcontroller unit (MCU) which achieves both high performance and ultra-low power by utilizing spintronics-based VLSI design technology and STT-MRAM memory.

Spintronics 200Mhz MCU (Tohoku University) photo
The researchers used several new techniques to create an efficient and fast device. Each module's power supply is controlled independently, which eliminates wasteful power consumption, while a memory controller and a reconfigurable accelerator module are used to relax data transfer bottlenecks. These new techniques enabled the researchers to achieve ultra-lower power consumptioN (47.14 uW) at 200Mhz.