Graphene

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. 

A team of researchers from CIC nanoGUNE, IKERBASQUE, IMEC and CNRS have reported a spintronic device that leverages proximity effects alone, specifically a 2D graphene-based spin valve. The functioning of this valve relies only on the proximity to the van der Waals magnet Cr₂Ge₂Te₆. Spin precession measurements showed that the graphene acquires both spin–orbit coupling and magnetic exchange coupling when interfaced with the Cr₂Ge₂Te₆. This leads to spin generation by both electrical spin injection and the spin Hall effect, while retaining spin transport. The simultaneous presence of spin–orbit coupling and magnetic exchange coupling also leads to a sizeable anomalous Hall effect.

The primary objective of this recent study was to tackle a long-standing research challenge, namely that of realizing the first-ever seamless 2D spintronic device. The spin valve they developed could enable the manipulation and transport of spin entirely in the 2D plane.

A Spanish-German collaboration recently studied graphene-cobalt-iridium heterostructures at BESSY II. The results show how two desired quantum-physical effects reinforce each other in these heterostructures, which could lead to new spintronic devices based on these materials.

Spintronics uses the spins of electrons to perform logic operations or store information. Ideally, spintronic devices could operate faster and more energy-efficiently than conventional semiconductor devices. However, it is still difficult to create and manipulate spin textures in materials. Graphene, a 2D honeycomb structure made of carbon atoms, is considered an interesting candidate for spintronic applications. Graphene is typically deposited on a thin film of heavy metal. At the interface between graphene and heavy metal, a strong spin-orbit coupling develops, which gives rise to different quantum effects, including a spin-orbit splitting of energy levels (Rashba effect) and a canting in the alignment of spins (Dzyaloshinskii-Moriya interaction). The spin canting effect is especially needed to stabilize vortex-like spin textures, known as skyrmions, which are particularly suitable for spintronics.

Researchers at CIC nanoGUNE BRTA, Charles University in Prague and IKERBASQUE have designed a new complex material with unique properties that could be beneficial for spintronics.

Twist engineering has emerged as a fascinating approach for modulating electronic properties in van der Waals heterostructures. While theoretical works have predicted the modulation of spin texture in graphene-based heterostructures by twist angle, experimental studies are lacking. In this recent work, by performing spin precession experiments, the team demonstrates tunability of the spin texture and associated spin–charge interconversion with twist angle in WSe₂/graphene heterostructures.

Researchers at the University of Wyoming, Pennsylvania State University, Northeastern University, The University of Texas at Austin, Colorado State University and Japan's National Institute for Materials Science have developed a method to control tiny magnetic states within ultrathin, two-dimensional van der Waals magnets - a process similar to how flipping a light switch controls a bulb.

The team developed a device known as a magnetic tunnel junction, which uses chromium triiodide - a 2D insulating magnet only a few atoms thick - sandwiched between two layers of graphene. By sending a tiny electric current called a tunneling current through this sandwich, the direction of the magnet's orientation of the magnetic domains (around 100 nanometers in size) can be dictated within the individual chromium triiodide layers.

Zhengzhou University researchers have synthesized a new material that combines graphene's remarkable properties with a strong response to magnetic fields. 

Graphene has a long spin lifetime and hyperfine interactions, making it potentially favorable for spintronics applications. Despite the recent discoveries of spin-containing graphene materials, graphene-based materials with room-temperature macroscopic ferromagnetism are extremely rare. In their recent study, room-temperature ferromagnetic amorphous graphene oxide (GO) was synthesized by introducing abundant oxygen-containing functional groups and C defects into single-layered graphene, followed by a self-assembly process under supercritical CO₂ (SC CO₂). 

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.

An interdisciplinary collaboration of researchers from South Korea and Singapore recently reported a significant advance towards achieving spin-polarized van der Waals heterostructures. The team designed a spin-selective memtransistor device using single-layer graphene deposited on the antiferromagnetic van der Waals magnetic insulator CrI₃. 

Transport measurements combined with first-principles calculations provide unprecedented insights into tailoring reciprocal magnetic proximity interactions to generate and probe proximitized magnetism in graphene at room temperature.

Researchers at the National University of Singapore (NUS), University of Science and Technology of China and the National Institute for Materials Science in Japan have developed a way to induce and directly quantify spin splitting in two-dimensional materials. 

Using this concept, they have experimentally achieved large tunability and a high degree of spin-polarization in graphene. This research achievement can potentially advance the field of two-dimensional (2D) spintronics, with applications for low-power electronics.

Researchers from Brown University, Michigan State University, Columbia University, Sandia National Laboratories in the U.S, Japan's National Institute for Materials Science and Austria's University of Innsbruck have observed low-energy collective excitations in twisted bilayer graphene near the magic angle, using a resistively detected electron spin resonance technique. 

For many years, scientists have been trying to directly manipulate the spin of electrons in 2D materials like graphene. Doing so could yield key advances in the world of 2D electronics, a field where super-fast, small and flexible electronic devices carry out computations based on quantum mechanics. Standing in the way is that the typical way in which scientists measure the spin of electrons — an essential behavior that gives everything in the physical universe its structure — usually doesn’t work in 2D materials. This makes it incredibly difficult to fully understand the materials and propel forward technological advances based on them. But a team of scientists led by Brown University researchers believe they now have a way around this longstanding challenge.