Memory

Researchers at the University of Utah and the University of California, Irvine (UCI), have set out to better understand a property known as spin-torque, that is crucial for the electrical manipulation of magnetization that’s required for the next generations of storage and processing technologies. 

The spintronic prototype device that exploits the anomalous Hall torque effect. Image from: University of Utah

The scientists have discovered a new type of spin–orbit torque, in a recent study that demonstrated a new way to manipulate spin and magnetization through electrical currents, a phenomenon that they’ve dubbed the anomalous Hall torque.

Researchers at the Research Center for Materials Nanoarchitectonics (MANA) recently proposed a method to create ferroelectric-ferromagnetic materials, opening doors to advancing spintronics and memory devices.

In 1831, Michael Faraday discovered the fundamental connection between electricity and magnetism, demonstrating that a changing magnetic field induces electric current in a conductor. In a recent study, MANA researchers proposed a method for designing ferroelectric-ferromagnetic (FE-FM) materials, which exhibit both ferroelectric and ferromagnetic properties, enabling the manipulation of magnetic properties using electric fields and vice versa. Such materials are highly promising for spintronics and memory devices. The advantage of FE-FM materials, extremely rare in nature, is their ability to achieve the cross-control by relatively low electric and magnetic fields. The study, led by Principal Researcher Igor Solovyev from MANA, NIMS, included contributions from Dr. Ryota Ono from MANA, NIMS, and Dr. Sergey Nikolaev from the University of Osaka, Japan.

A team of Tohoku University researchers recently investigated a cobalt-manganese-iron alloy thin film that demonstrates a high perpendicular magnetic anisotropy (PMA) - key aspects for fabricating MRAM devices using spintronics.

"This is the first time a cobalt-manganese-iron alloy has strongly shown large PMA," says Professor Shigemi Mizukami from Tohoku University, "We previously discovered this alloy showed a high tunnel magnetoresistance (TMR) effect, but it is rare that an alloy potentially shows both together." For example, Iron-cobalt-boron alloys, which are conventionally used for MRAM, possess both traits, but their PMA is not strong enough.

Researchers from Korea have designed a new MRAM structure, based on graphene, that offers higher efficiency (and lower heat generation) compared to existing MRAM solutions. The design of the MRAM device is based on a graphene layer sandwiched between a magnetic insulator (yttrium iron garnet) and a ferroelectric material (PVDF-TrFE). Upon application of a voltage pulse, the current flow through the graphene is altered, enabling the storage of binary data based on this current direction.

The recent study demonstrates non-volatile control of spin-charge conversion at room temperature in graphene-based heterostructures through Fermi level tuning. The team used a polymeric ferroelectric film to induce non-volatile charging in graphene. To demonstrate the switching of spin-to-charge conversion, the scientists performed ferromagnetic resonance and inverse Edelstein effect experiments. 

Researchers from the Tokyo University of Science have proposed a novel magnetic RAM-based architecture that leverages spintronics to realize smaller, more efficient AI-capable circuits.

(a) Structure of the proposed neural network, which uses three-valued gradients during backpropagation (training) rather than real numbers, thus minimizing computational complexity. (b) A novel magnetic RAM cell leveraging spintronics for implementing the proposed technique in a computing-in-memory architecture.   

Artificial intelligence (AI) and the Internet of Things (IoT) are two technological fields that have been developing at an increasingly fast pace over the past decade. By excelling at tasks such as data analysis, image recognition, and natural language processing, AI systems have become undeniably powerful tools in both academic and industry settings. Meanwhile, miniaturization and advances in electronics have made it possible to massively reduce the size of functional devices capable of connecting to the Internet. Engineers and researchers alike foresee a world where IoT devices are ubiquitous, comprising the foundation of a highly interconnected world. However, bringing AI capabilities to IoT edge devices presents a significant challenge. Artificial neural networks (ANNs)—one of the most important AI technologies—require substantial computational resources. Meanwhile, IoT edge devices are inherently small, with limited power, processing speed, and circuit space. Developing ANNs that can efficiently learn, deploy, and operate on edge devices is a major hurdle.

TDK Corporation has announced the development of a neuromorphic element called a “spin-memristor” that has very low power consumption. By mimicking the energy-efficient operation of the human brain, this element could cut the power consumption of AI applications down to 1/100th of traditional devices. Collaborating with the French research organization CEA (Alternative Energies and Atomic Energy Commission), TDK has shown that its “spin-memristor” can serve as the basic element of a neuromorphic device. 

Going forward, TDK will collaborate with the Center for Innovative Integrated Electronic Systems at Tohoku University on the practical development of the technology.

Researchers from the University of Nebraska-Lincoln and University of Latvia have announced "a breakthrough in antiferromagnetic spintronics" that could expand the nanotechnology’s capabilities, which have been limited by their need for excessive power. 

The team showed that introducing boron — a process called B-doping — into magnetoelectric oxides can control magnetic fields at the high temperatures prevalent in electronics. This long has been the “holy grail” of such research, said Christian Binek, Charles Bessey Professor of physics.

Researchers from Tohoku University and Toho University have demonstrated chirality switching by electric current pulses at room temperature in a thin-film MnAu₂ helimagnetic conductor. The team also succeeded in detecting the chirality at zero magnetic fields by means of simple transverse resistance measurement utilizing the spin Berry phase in a bilayer device composed of MnAu₂ and a spin Hall material Pt. These results may pave the way to helimagnet-based spintronics. 

Helimagnetic structures, in which the magnetic moments are spirally ordered, host an internal degree of freedom called chirality corresponding to the handedness of the helix. The chirality seems quite robust against disturbances and is therefore promising for next-generation magnetic memory. While the chirality control was recently achieved by the magnetic field sweep with the application of an electric current at low temperature in a conducting helimagnet, problems such as low working temperature and cumbersome control and detection methods have to be solved in practical applications.

Researchers at North Carolina State University, University of Illinois at Urbana-Champaign, Duke University and Sivananthan Laboratories have relied on a printable organic polymer, that assembles into chiral structures when printed, to reliably measure the amount of charge produced in spin-to-charge conversion within a spintronic material at room temperature. 

The polymer’s tunable qualities and versatility make it desirable not only for less expensive, environmentally friendly, printable electronic applications, but also for use in understanding chirality and spin interactions more generally.

The EU project 2DSPIN-TECH aims to pave the way for significantly faster and more energy-efficient computer memories. Last week, the project kickoff event took place, with seven partners and €4 million in funding. The project spans three years and is conducted within the framework of the EU’s Graphene Flagship, a multibillion-dollar initiative launched over a decade ago to stimulate research and innovation in graphene and other two-dimensional materials.

“Our ambition is to create novel spintronic memory devices based on two-dimensional quantum materials, significantly reducing energy consumption, promoting sustainability, and enhancing the overall performance of computer memories. This is crucial for the future of information technology,” says Saroj Dash, Professor of quantum component physics at Chalmers University of Technology and coordinator of 2DSPIN-TECH.