Research / Technical

Researchers design novel graphene-based spin valve that relies on van der Waals magnet proximity

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.

Read the full story Posted: Nov 22,2024

Researchers succeed in capturing 3D X-ray images of a Skyrmion

Magnetic skyrmions have so far been treated as two-dimensional spin structures characterized by a topological winding number. However, in real systems with the finite thickness of the device material being larger than the magnetic exchange length, the skyrmion spin texture extends into the third dimension and cannot be assumed as homogeneous.

A 3D reconstruction of a skyrmion derived from X-ray images. Credit: Berkeley Lab

Researchers at Lawrence Berkeley National Laboratory, Swiss Light Source (Paul Scherrer Institute) and Western Digital Research Center have used soft x-ray laminography to reconstruct, with about 20-nanometer spatial (voxel) size, the full three-dimensional spin texture of a skyrmion in an 800-nanometer-diameter and 95-nanometer-thin disk patterned into a 30× [iridium/cobalt/platinum] multilayered film.

Read the full story Posted: Oct 23,2024

Researchers identify light-induced Kondo-like exciton-spin interaction in neodymium(II) doped hybrid perovskite

In a recent sturdy, researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and Northern Illinois University discovered that they could use light to detect the spin state in a class of materials called perovskites (specifically in this research methylammonium lead iodide, or MAPbI3). 

To understand spin, consider electrons orbiting the atomic nucleus. When atoms are close together, they can share some of their outer electrons, which creates a bond between them. Each bond contains two electrons that are ​“paired,” meaning they share an orbital — the region where they move. Now, each of these paired electrons has one of two possible spin states: spin up or spin down. If one electron is spin up, the other is spin down. Since we can’t know exactly which electron has which spin without looking at them, we say they exist in a quantum superposition — a state where they are both spin up and spin down until observed.

Read the full story Posted: Oct 16,2024

Researchers examine thermal contribution to current-driven antiferromagnetic-order switching

researchers at the University of Illinois Urbana-Champaign have used new a experimental technique to measure heating in spintronic devices, allowing direct comparison to other effects. The researchers say that this technique can be used to select spintronic materials whose magnetic behavior is minimally impacted by heating, leading to faster devices.

"Spintronic devices depend on the ability to change magnetization using electric currents, but there are two possible explanations for it: electromagnetic interactions with the current, or the increase in temperature caused by the current," said Axel Hoffmann, project lead and Illinois materials science and engineering professor. "If you want to optimize the function of the device, you have to understand the underlying physics. That's what our approach helped us to do."

Read the full story Posted: Sep 26,2024

Researchers find that boron doping of magnetoelectric oxides can help control magnetic fields at high temperatures

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.

Read the full story Posted: Sep 23,2024

Researchers gain valuable insight by studying graphene-cobalt-iridium heterostructures at BESSY II

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.

Read the full story Posted: Sep 21,2024

Researchers examine coherent spin dynamics between electron and nucleus within a single atom

Researchers from Delft University of Technology and Karlsruhe Institute of Technology (KIT) have initiated a controlled movement in the heart of an atom, causing the atomic nucleus to interact with one of the electrons in the outermost shells of the atom. This electron could be manipulated and read out through the needle of a scanning tunneling microscope. The research offers prospects for storing quantum information inside the nucleus, where it is safe from external disturbances.

The team studied a single titanium atom - a Ti-47 atom, that has one neutron less than the naturally abundant Ti-48, which makes the nucleus slightly magnetic. This magnetism, or the 'spin', can be seen as a sort of compass needle that can point in various directions. The orientation of the spin at a given time constitutes a piece of quantum information.

Read the full story Posted: Sep 14,2024

Researchers develop a generic approach towards intrinsic magnetic second-order topological insulators

Researchers from Monash University, part of the FLEET Centre, and China's Weifang University, have reported a generic approach towards intrinsic magnetic second-order topological insulators - materials that can be beneficial for spintronics.

Two-dimensional ferromagnetic semiconductors, such as CrI3, Cr2Ge2Te6, and VI3, have been extensively studied in recent years and are fundamental to spintronics. Topological insulators are materials with unique properties where the interior is insulating, but the boundary can conduct electrons. In three-dimensional topological insulators like Bi2Se3, the surface hosts two-dimensional Dirac fermions. Second-order topological insulators, a new concept extending the idea of topological insulators, exhibit (m-2)-dimensional boundary states in m-dimensional materials, such as one-dimensional hinge states in three-dimensional materials and zero-dimensional corner states in two-dimensional materials.

Read the full story Posted: Sep 12,2024

Researchers examine magnetic tunnel junction based on bilayer LaI2 as perfect spin filter device

Researchers at King Abdullah University of Science and Technology (KAUST) and Khalifa University of Science and Technology have investigated the transmission, tunneling magnetoresistance ratio and spin injection efficiency of bilayer LaI2 using a combination of first-principles calculations and the non-equilibrium Green’s function method. 

Multilayer graphene electrodes were used by the team, to build a magnetic tunnel junction with bilayer LaI2 as ferromagnetic barrier. The magnetic tunnel junction reportedly proved to be a perfect spin filter device with an impressive tunneling magnetoresistance ratio of 653% under a bias of 0.1 V and a still excellent performance in a wide bias range. The team said that in combination with the obtained high spin injection efficiency, this could hold great potential from an application point of view.

Read the full story Posted: Sep 03,2024

Researchers develop method to control the quantum states of single electron spins using spin-polarized currents

Researchers from ETH Zurich recently developed a method to control the quantum states of single electron spins using spin-polarized currents, which could enhance quantum computing technologies. The new technique offers more precise, localized control compared to traditional methods using electromagnetic fields, potentially improving the manipulation of quantum states in devices like qubits. 

Control over quantum systems is typically achieved by time-dependent electric or magnetic fields. Alternatively, electronic spins can be controlled by spin-polarized currents. In their recent work, the team demonstrated coherent driving of a single spin by a radiofrequency spin-polarized current injected from the tip of a scanning tunneling microscope into an organic molecule. With the excitation of electron paramagnetic resonance, the scientists established dynamic control of single spins by spin torque using a local electric current. In addition, their work highlights the dissipative action of the spin-transfer torque, in contrast to the nondissipative action of the magnetic field, which allows for the manipulation of individual spins based on controlled decoherence.

Read the full story Posted: Aug 16,2024