Antiferromagnetism - Page 4

A team of researchers from Ames Laboratory and Iowa State University, as well as collaborators from the United States, Germany, and the United Kingdom, have reported on new Fermi arcs that can be controlled through magnetism and could be the future of electronics based on electron spins.

During the team's investigation of the rare-earth monopnictide NdBi (neodymium-bismuth), thet discovered a new type of Fermi arc that appeared at low temperatures when the material became antiferromagnetic, i.e., neighboring spins point in opposite directions. Fermi surfaces in metals are a boundary between energy states that are occupied and unoccupied by electrons. Fermi surfaces are normally closed contours forming shapes such as spheres, ovoids, etc. Electrons at the Fermi surface control many properties of materials such as electrical and thermal conductivity, optical properties, etc. In extremely rare occasions, the Fermi surface contains disconnected segments that are known as Fermi arcs and often are associated with exotic states like superconductivity.

A team of researchers from Goethe University, Fritz Haber Institute of the Max Planck Society, Uppsala University, HZB, Paul Scherrer Institute and the Basque Foundation for Science has identified materials that have surprisingly fast properties for spintronics.

"You have to imagine the electron spins as if they were tiny magnetic needles which are attached to the atoms of a crystal lattice and which communicate with one another," says Cornelius Krellner, Professor for Experimental Physics at Goethe University Frankfurt. How these magnetic needles react with one another fundamentally depends on the properties of the material. To date ferromagnetic materials have been examined in spintronics above all; with these materials - similarly to iron magnets - the magnetic needles prefer to point in one direction. In recent years, however, the focus has been placed on so-called antiferromagnets to a greater degree, because these materials are said to allow for even faster and more efficient switchability than other spintronic materials.

Researchers in the UK, South Korea and the U.S recently discovered that the two-dimensional layered magnet chromium triiodide (CrI₃) acts as a topological magnon insulator in the absence of an external magnetic field. This result could have potential applications for so-called dissipationless spintronics in which electrons are used to transmit and store information in an ultra-fast and ultra-low power fashion.

Thanks to detailed neutron scattering measurements and fine analysis, the team has found that this phenomenon comes from the way in which the layers in the material are stacked together. That is, while a single layer of CrI₃ is ferromagnetic, two stacked layers are antiferromagnetic which counterintuitively is different from that in ferromagnetic bulk.

Researchers from Daegu Gyeongbuk Institute of Science and Technology (DGIST) in Korea have demonstrated a novel route to tune and control the magnetic domain wall motions employing combinations of useful magnetic effects inside very thin film materials. The research offers a new insight into spintronics and a step towards new ultrafast, ultrasmall, and power-efficient IT devices.

The new study demonstrates a new way to handle information processing using the movement of the magnetic states of the thin film device. It takes advantage of some unusual effects that occur when materials with contrasting types of magnetic material are squashed together. The research focuses on a device that combines ferromagnetic and antiferromagnetic materials, in which the directions of electron spins align differently within the respective magnetic materials.

An international collaboration led by RMIT has achieved record-high electron doping in a layered ferromagnet, causing magnetic phase transition with significant promise for future electronics.

Control of magnetism (or spin directions) by electric voltage is vital for developing future, low-energy high-speed nano-electronic and spintronic devices, such as spin-orbit torque devices and spin field-effect transistors. Ultra-high-charge, doping-induced magnetic phase transition in a layered ferromagnet allows promising applications in antiferromagnetic spintronic devices.

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.

Scientists from Daegu Gyeongbuk Institute of Science and Technology (DGIST) and Korea Research Institute of Standards and Science (KRISS) have found a new way to control the alignment state of magnetic atoms in an antiferromagnetic material, showing promise for the development of tiny sensors and memory devices.

The researchers' new approach features a controllable exchange bias effect, which enables the asymmetric magnetic actions of devices comprised of complex combination structure of different types of magnetic materials.

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 the University of California, Riverside, have used a nanoscale synthetic antiferromagnet to control the interaction between magnons — research that could lead to faster and more energy-efficient computers.

In ferromagnets, electron spins point in the same direction. To make future computer technologies faster and more energy-efficient, spintronics research employs spin dynamics — fluctuations of the electron spins — to process information. Magnons, the quantum-mechanical units of spin fluctuations, interact with each other, leading to nonlinear features of the spin dynamics. Such nonlinearities play a central role in magnetic memory, spin torque oscillators, and many other spintronic applications.

Antiferromagnetic (AFM) spintronics are devices or components for electronics that couple a flowing current of charge to the ordered spin 'texture' of specific materials. The successful development of AFM spintronics could have important implications, as it could lead to the creation of devices or components that surpass Moore's law. But it seems that finding materials with the exact characteristics necessary to fabricate AFM spintronics is highly challenging.

Researchers at the Lawrence Berkeley National Laboratory, UC Berkeley and the National High Magnetic Field Laboratory in Tallahassee have recently identified a new quantum material (Fe_1/3 + _δNbS₂) that could be used to fabricate AFM spintronic devices. In their most recent papers, they demonstrated the feasibility of using this material for two AFM spintronics applications.