Research / Technical - Page 14

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 team of researchers from Sweden, Finland and Japan have designed a semiconductor component in which information can be efficiently exchanged between electron spin and light at room temperature and above.

Developments in spintronics in recent decades have been based on the use of metals, and these have been highly significant for the possibility of storing large amounts of data. There would, however, be several advantages in using spintronics based on semiconductors, in the same way that semiconductors form the backbone of today's electronics and photonics.

Recent studies have suggested that 2D skyrmions could be the genesis of a 3D spin pattern called hopfions, but no one had been able to experimentally prove that magnetic hopfions exist on the nanoscale. Now, a team of researchers co-led by Berkeley Lab reported the first demonstration and observation of 3D hopfions emerging from skyrmions at the nanoscale in a magnetic system.

Artist’s drawing of characteristic 3D spin texture of a magnetic hopfion. Berkeley Lab scientists have created and observed 3D hopfions. Credit: Peter Fischer and Frances Hellman/Berkeley Lab (from Phys.org)

The researchers say that their discovery is a major step forward in realizing high-density, high-speed, low-power, yet ultrastable magnetic memory devices that exploit the intrinsic power of electron spin.

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 from Oak Ridge National Laboratory (ORNL), University of California and Lawrence Berkeley National Laboratory have discovered the existence of elusive spin dynamics in quantum mechanical systems.

The team successfully simulated and measured spins - magnetic particles, which can exhibit a motion known as Kardar-Parisi-Zhang in solid materials at varying temperatures. Up until now, scientists have only found evidence of the spin dynamics in soft matter and other classical materials.

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.

Researchers from the Madrid Institute for Advanced Studies in Nanoscience (IMDEA) and the University of Sevilla have measured for the first time the electrical conductivity of a single carbon nanotube with spin-crosslinked molecules inside it.

Iron-based SCO molecules encapsulated in a single carbon nanotube. Credit: Nature Communications

Magnetic molecules could add a new twist to conventional electronics. In particular, spin-crossover (SCO) molecules belong to a family of zero-dimensional (0D) functional units that display a radical spin switch triggered by an electro-structural change activatable by external stimulus such as light, pressure or temperature. The spin switch confers SCO molecules excellent capabilities and functionalities for implementation in nano-electronics. However, their insulating character has so far prevented these molecules from being fully exploited. Several groups have embedded SCO molecules into matrices of conductive materials but the results have not been fully compatible with the requirements of nanoscale devices.

A team of researchers from the National Renewable Energy Laboratory (NREL) and the University of Utah has developed a new type of LEDs that utilizes spintronics without needing a magnetic field, magnetic materials or cryogenic temperatures.

“The companies that make LEDs or TV and computer displays don’t want to deal with magnetic fields and magnetic materials. It’s heavy and expensive to do it,” said Valy Vardeny, distinguished professor of physics and astronomy at the University of Utah. “Here, chiral molecules are self-assembled into standing arrays, like soldiers, that actively spin polarize the injected electrons, which subsequently lead to circularly polarized light emission. With no magnetic field, expensive ferromagnets and with no need for extremely low temperatures. Those are no-nos for the industry.”

An international research team, led by the University at Buffalo, has reported an advancement that could help give graphene magnetic properties. The researchers describe in their work how they paired a magnet with graphene, and induced what they describe as “artificial magnetic texture” in the nonmagnetic material. This achievement may, according to the researchers, push forward the spintronics field.

The image shows eight electrodes around a 20-nanometer-thick magnet (white rectangle) and graphene (white dotted line). Credit: University at Buffalo.

“Independent of each other, graphene and spintronics each possess incredible potential to fundamentally change many aspects of business and society. But if you can blend the two together, the synergistic effects are likely to be something this world hasn’t yet seen,” says lead author Nargess Arabchigavkani, who performed the research as a PhD candidate at UB and is now a postdoctoral research associate at SUNY Polytechnic Institute.

A new theory by Rice University scientists could boost the field of spintronics. Materials theorist Boris Yakobson and graduate student Sunny Gupta at Rice's Brown School of Engineering describe the mechanism behind Rashba splitting, an effect seen in crystal compounds that can influence their electrons' up or down spin states, analogous to on or off in common transistors.

The left shows the crystal structure of a MoTe2

The Rice model characterizes single layers to predict heteropairs two-dimensional bilayers that enable large Rashba splitting. These would make it possible to control the spin of enough electrons to make room-temperature spin transistors, a far more advanced version of common transistors that rely on electric current.