Recent Spintronic News - Page 2

While the field of spintronics tries to leverage the spin angular momentum of electrons to develop new technologies, these particles' orbital momentum has so far been rarely considered. Currently, generating an orbital current (i.e., a flow of orbital angular momentum) remains far more challenging than generating a spin current. Nonetheless, approaches to successfully leveraging the orbital angular momentum of electrons could open the possibility for the development of a new class of devices called orbitronics.

Researchers at Japan's Keio University and Germany's Johannes Gutenberg University have reported the successful generation of an orbital current from magnetization dynamics, a phenomenon called orbital pumping. Their outlines a promising approach that could allow engineers to develop new technologies leveraging the orbital angular momentum of electrons.

Researchers from National Renewable Energy Laboratory (NREL), University of Utah, Université de Lorraine CNRS and University of Colorado Boulder have improved upon their previous work, that included incorporating a perovskite layer that allowed the creation of a new type of polarized light-emitting diode (LED) that emits spin-controlled photons at room temperature without the use of magnetic fields or ferromagnetic contacts. In their latest work, they have gone a step further by integrating a III-V semiconductor optoelectronic structure with a chiral halide perovskite semiconductor.

The team transformed an existing commercialized LED into one that also controls the spin of electrons. The results could provide a pathway toward transforming modern optoelectronics, a field that relies on the control of light and encompasses LEDs, solar cells, and telecommunications lasers, among other devices.

Researchers at MIT, DEVCOM Army Research Laboratory, The Ohio State University, and University of Ottawa have reported unique electron mobility in a new crystal film that could be the basis for wearable thermoelectric and spintronic devices.

A material with a high electron mobility is like a highway without traffic, and the electrons that flow into the material experience movement without any obstacles to slow or scatter them off their path. The higher a material’s electron mobility, the more efficient its electrical conductivity, and the less energy is lost or wasted as electrons move through. Advanced materials that exhibit high electron mobility will be essential for more efficient and sustainable electronic devices that can do more work with less power.

Spintronics relies on the transport of spin currents for computing and communication applications. New device designs would be possible if this spin transport could be carried out by both electrons and magnetic waves called magnons. But spin transport via magnons typically requires electrically insulating magnets—materials that cannot be easily integrated with silicon electronics. Recently, a novel way to bypass that requirement has been developed by researchers at ETH Zürich, Bavarian Academy of Sciences, Technical University of Munich, University of Konstanz, Munich Center for Quantum Science and Technology (MCQST) and Autonomous University of Madrid.

The researchers say that this finding could have important implications for both spintronic applications and fundamental research on spin transport. To demonstrate their concept, the scientists placed two magnetic, metallic strips—each hosting coupled electrons and magnons—on a nonmagnetic, insulating substrate. In the first strip, the researchers converted electron charge currents to electron spin currents. These spin currents were transferred first to the magnons in the same strip, then across the substrate to the magnons in the second strip, and finally to the electrons in the second strip. The researchers detected this spin transport by converting the electron spin currents in the second strip to charge currents.

Researchers at Osaka Metropolitan University, University of Nottingham, Czech Academy of Sciences, Diamond Light Source, ohannes Kepler University Linz, Johannes Gutenberg Universität Mainz, TU Wien and Masaryk University have used symmetry, ab initio theory, and experiments to explore x-ray magnetic circular dichroism (XMCD) in the altermagnetic class. The international research group recently pioneered a new method to identify altermagnets, using manganese telluride (α-MnTe) as a testbed. 

Magnetic materials have traditionally been classified as either ferromagnetic or antiferromagnetic. However, there appears to be a third class of magnetic materials exhibiting what is known as 'altermagnetism'. In ferromagnetic materials, all the electron spins point in the same direction, while in antiferromagnetic materials, the electron spins are aligned in opposite directions, half pointing one way and half the other, canceling out the net magnetism. Altermagnetic materials are proposed in theory to possess properties combining those of both antiferromagnetic and ferromagnetic materials. One potential application of altermagnetic materials is in spintronics technology, which aims to utilize the spin of electrons effectively in electronic devices such as next-generation magnetic memories. However, identifying altermagnets has been a challenge.

Researchers at the University of Cambridge, University of Technology Sydney, The Australian National University and Hitachi Europe have found that a ‘single atomic defect' in a layered 2D material, hexagonal Boron Nitride (hBN), can hold onto quantum information for microseconds at room temperature. This highlights the potential of 2D materials in advancing quantum technologies.

The scientists have shown that hBN exhibits spin coherence under ambient conditions, and that these spins can be controlled with light. Spin coherence refers to an electronic spin being capable of retaining quantum information over time. The discovery is significant as materials that can host quantum properties under ambient conditions are quite rare.

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.

Researchers at North Carolina State University, University of Pittsburgh, University of Illinois at Urbana-Champaign, Chinese Academy of Sciences and Beijing Normal University have studied how the spin information of an electron, called a pure spin current, moves through chiral materials. 

They found that the direction in which the spins are injected into chiral materials affects their ability to pass through them. These chiral “gateways” could be used to design energy-efficient spintronic devices for data storage, communication and computing.

An international team of researchers, led by scientists from the CNRS, has reported that the magnetic nanobubbles known as skyrmions can be moved by electrical currents, attaining record speeds up to 900 m/s.

Magnetic skyrmions are topological magnetic textures that hold great promise as nanoscale bits of information in memory and logic devices. While room-temperature ferromagnetic skyrmions and their current-induced manipulation have been demonstrated, their velocity has thus far been limited to about 100 meters per second, which is too slow for computing applications. In addition, their dynamics are perturbed by the skyrmion Hall effect, a motion transverse to the current direction caused by the skyrmion topological charge. 

Researchers from Tohoku University, University of Tokyo, Australian Nuclear Science and Technology Organization, High Energy Accelerator Research Organization and Comprehensive Research Organization for Science and Society have found that the spin current signal changes direction at a certain magnetic temperature and diminishes at lower temperatures.

Spintronics uses electrons’ intrinsic spin, which is vital to the field, to regulate the flow of the spin degree of freedom, that is, spin currents. Scientists are continually exploring new ways to manage spintronics for future uses. Detecting spin currents is quite complicated and necessitates the use of macroscopic voltage measurement, which examines the entire voltage fluctuations across a material. However, a major stumbling block has been a lack of understanding of how the spin current flows or propagates inside the material.