Spin current - Page 4

Researchers at Tohoku University and the Japan Atomic Energy Agency (JAEA) have reported a new spintronic phenomenon – a persistent rotation of chiral-spin structure.

The researchers studied the response of chiral-spin structure of a non-collinear antiferromagnet Mn3Sn thin film to electron spin injection and found that the chiral-spin structure shows persistent rotation at zero magnetic field. Moreover, their frequency can be tuned by the applied current.

A team of researchers from The University of Groningen and Columbia University have found that 2D spin-logic devices could benefit from magnetic graphene that can efficiently convert charge to spin current, and can transfer this spin-polarization over long distances.

Graphene is known amongst 2D materials for transporting spin information, but cannot generate spin current unless its properties are modified – conventionally cobalt ferromagnetic electrodes are used for injecting and detecting the spin signal.

Researchers at Aalto University have developed a new device for spintronics, which could be seen as a step towards using spintronics to make computer chips and devices for data processing and communication technology.

Schematic of the experimental geometry. Image from article

"If you use spin waves, it's transfer of spin, you don't move charge, so you don't create heating," says Professor Sebastiaan van Dijken, who leads the group that wrote the paper. The device the team made is a Fabry-Pérot resonator, a well-known tool in optics for creating beams of light with a tightly controlled wavelength. The spin-wave version made by the researchers in this work allows them to control and filter waves of spin in devices that are only a few hundreds of nanometres across.

A research team from the Max Planck Institute for the Structure and Dynamics of Matter (MPSD), Tianjin University in China and Tohoku University in Japan recently reported that, when driven out of equilibrium by magnetic fields, a universal Doppler effect limits the maximal spin current in magnetic insulators.

This finding is a surprising analogy to what happens in superconductors driven by electric fields and could provide a fundamental design principle for future nano-devices with computing science and power applications.

Researchers used the Advanced Photon Source (APS), a U.S. Department of Energy Office of Science User Facility at DOE’s Argonne National Laboratory, to study ways to manipulate electron spins and develop new materials for spintronics. The research team, led by Chang-Beom Eom at the University of Wisconsin-Madison, designed a new material that has three times the storage density and uses much less power than other spintronics devices.

Not many of these types of materials exist, especially ones that work at room temperature like this one. If the new material can be perfected, it could aid in the creation of more efficient electronic devices with less tendency to overheat. This is particularly important for advancing the development of low-power computing and fast magnetic memory.

Scientists at the U.S. Department of Energy's Ames Laboratory, along with collaborators at Brookhaven National Laboratory and the University of Alabama at Birmingham, have discovered a light-induced switch that twists the crystal lattice of the material, switching on a giant electron current that appears to be nearly dissipationless. The discovery was made in a category of topological materials that holds great promise for spintronics, topological effect transistors, and quantum computing.

Weyl and Dirac semimetals can host exotic, nearly dissipationless, electron conduction properties that take advantage of the unique state in the crystal lattice and electronic structure of the material that protects the electrons from doing so. These anomalous electron transport channels, protected by symmetry and topology, don't normally occur in conventional metals such as copper. After decades of being described only in the context of theoretical physics, there is growing interest in fabricating, exploring, refining, and controlling their topologically protected electronic properties for device applications. For example, wide-scale adoption of quantum computing requires building devices in which fragile quantum states are protected from impurities and noisy environments. One approach to achieve this is through the development of topological quantum computation, in which qubits are based on "symmetry-protected" dissipationless electric currents that are immune to noise.

Researchers at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Yale University have demonstrated the ability to control spin dynamics in magnetic materials by altering their thickness. The new study could lead to smaller, more energy-efficient electronic devices.

“Instead of searching for different materials that share the right frequencies, we can now alter the thickness of a single material—iron, in this case—to find a magnetic medium that will enable the transfer of information across a device,” said Brookhaven physicist and principal investigator Valentina Bisogni.

Researchers have recently demonstrated the long-range transport of magnetic hedgehogs, 3D topological spin structures that are often observed in common magnets. Their work could have important implications for the development of spintronic devices.

Nonlocal transport measurement of hedgehog currents in a three-dimensional insulating magnet. Image from article

Magnetic insulators are a class of materials widely used worldwide, mainly due to their ability to conduct electrical charges. Just like metals conduct electrical charges, magnetic insulators can conduct spins. Nonetheless, as spins are rarely conserved in materials and tend to disappear over long distances, so far, using magnetic insulators to achieve long-range transport has proved highly challenging.

University of Tokyo researchers have created a material that confines electrons in one dimension in the form of a special bismuth-based crystal known as a high-order topological insulator.

To create spintronic devices, new materials need to be designed that take advantage of quantum behaviors not seen in everyday life. For spintronic applications, a new kind of electronic material is required - a topological insulator. It differs from other materials by insulating throughout its bulk, but conducting only along its surface. And what it conducts is not the flow of electrons themselves, but a property of them known as their spin or angular momentum.

Researchers from Exeter University, in collaboration with the Universities of Oxford, California Berkeley, and the Advanced and Diamond Light Source have experimentally demonstrated that high frequency alternating spin currents can be transmitted by, and sometimes amplified within, thin layers of antiferromagnetic NiO.

The researchers say that these results demonstrate that the spin current in thin NiO layers is mediated by evanescent spin waves, a mechanism akin to quantum mechanical tunnelling. This could lead to more efficient future wireless communication technology based on such antiferromagnetic spintronics devices.