Antiferromagnetism - Page 4

A group of physicists, led by Prof. SHAO Dingfu from the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Sciences (CAS), has predicted "parallel circuits" of spin currents in antiferromagnets, which can accelerate spintronics.

Spin-polarized electric currents play a central role in spintronics, due to the capabilities of manipulation and detection of magnetic moment directions for writing and reading 1s and 0s. Currently, most spintronic devices are based on ferromagnets, where the net magnetizations can efficiently spin polarize electric currents. Antiferromagnets, with opposite magnetic moments aligned alternately, are not quite as investigated but may promise even faster and smaller spintronic devices.

Researchers from the University of Nottingham, Diamond Light Source, Czech Academy of Sciences and The University of New South Wales have shown for the first time how electrical creation and control of magnetic vortices in an antiferromagnet can be achieved, a discovery that could increase the data storage capacity and speed of next generation devices.

The team used magnetic imaging techniques to map the structure of newly formed magnetic vortices and demonstrate their back-and-forth movement due to alternating electrical pulses. 

Researchers from Tohoku University in Japan, University of California Riverside and the Massachusetts Institute of Technology detail a decade of research advancements in the emerging field of antiferromagnetic spintronics that holds the promise of moving beyond today’s world of electrons moving through semiconductors.

As computers and other electronic devices become faster and more powerful, they are coming closer to a physical limitation caused by heat generated by the electrons that carry information as they move through semiconductors. “Making heat is a fundamental limit that will prevent the further development of electronic devices. So, we are basically hitting a bottleneck because our computers are way faster than they used to be two decades ago,” said Ran Cheng, an assistant professor of electrical and computer engineering with UCR’s Bourns College of Engineering. Workarounds like cooling systems can go only so far as artificial intelligence, machine learning, video streaming, and other applications demand faster and faster computer processing and memory retrievals.

Researchers from North Carolina State University, University of North Carolina at Chapel Hill, Massachusetts Institute of Technology (MIT),  National Renewable Energy Laboratory, Duke University, Wayne State University and The Hong Kong University of Science and Technology have created a mixed magnon state in an organic hybrid perovskite material by utilizing the Dzyaloshinskii-Moriya-Interaction (DMI).

The resulting material has potential for processing and storing quantum computing information. The work also expands the number of potential materials that can be used to create hybrid magnonic systems.

Researchers from Tohoku University, University of California Riverside and Massachusetts Institute of Technology (MIT) have highlighted a series of critical achievements in antiferromagnetic spintronics (including their own contributions), revealing an emerging frontier distinguished by the coherent spin dynamics of antiferromagnets. 

Within antiferromagnetic spintronics, scientists have exerted a lot of efforts on the switching and readout of static magnetic order. But coherent spin dynamics, the key to exploring the wave features of spins and integrating spintronics with quantum and neuromorphic technologies, has only received attention very recently. "The coherent spin dynamics of antiferromagnets exhibits a lot more intriguing features than that of ferromagnets," says Jiahao Han, a JSPS Research Fellow working at the Research Institute of Electrical Communication (RIEC), Tohoku University. "By harnessing this unique property, the team has been pursuing breakthroughs that eventually form a new chapter named coherent antiferromagnetic spintronics."

A team led by researchers at the National Institute of Standards and Technology (NIST), the University of South Florida (USF), Harvey-Mudd College and the University of the District of Columbia has discovered a route toward reducing the sputter damage during growth of Nanolayered Pt/Co/Ir-based Synthetic Antiferromagnets that delivers significant improvements in perpendicular magnetic anisotropy and interlayer exchange coupling energy.

Synthetic antiferromagnets (SAFs) are a core component for top-pinned magnetic tunnel junction memory systems in semiconductor production. Establishing low-damage sputtering techniques to protect the multiple interfaces between sub-nm thick constituent layers delivers improved SAF properties could be key to data retention in high-density, sub-10 nm diameter magnetic memory arrays.

Researchers from Germany's Max Planck Institute of Microstructure Physics have reported a lift-off and transfer method to fabricate three-dimensional racetrack memories from freestanding magnetic heterostructures grown on a water-soluble sacrificial release layer.

The fabrication of three-dimensional nanostructures is key to the development of next-generation nanoelectronic devices with a low device footprint. Magnetic racetrack memories encode data in a series of magnetic domain walls that are moved by current pulses along magnetic nanowires. To date, most studies have focused on two-dimensional racetracks.

Researchers from Oak Ridge National Laboratory, Helmholtz-Zentrum Berlin (HZB) and University of Amsterdam have used inelastic neutron scattering and methods of integrability to experimentally observe and theoretically describe a local, coherent, long-lived, quasiperiodically oscillating magnetic state emerging out of the distillation of propagating excitations following a local quantum quench in a Heisenberg antiferromagnetic chain.

This “quantum wake” displays similarities to Floquet states, discrete time crystals and nonlinear Luttinger liquids. The team also showed how this technique reveals the non-commutativity of spin operators, and is thus a model-agnostic measure of a magnetic system’s “quantumness.”

A team of researchers, led by Igor Barsukov at the University of California, Riverside, in collaboration with researchers at Helmholtz-Zentrum Dresden-Rossendorf, the University of Utah, and the University of California, Irvine, has demonstrated efficient spin transport in an antiferromagnet/ferromagnet hybrid that remains robust up to room temperature. The researchers observed coupling of magnonic subsystems in the antiferromagnet and ferromagnet and recognized its importance in spin transport, a key process in the operation of spin-based devices. 

Antiferromagnets have zero net magnetization and are insensitive to external magnetic field perturbations. Antiferromagnetic spintronic devices hold great promise for creating future ultra-fast and energy-efficient information storage, processing, and transmission platforms, potentially leading to faster and more energy-efficient computers.  However, in order to be useful for applications impacting everyday life, the devices need to be able to operate at room temperature. One of the key factors in realizing antiferromagnetic spintronics is the injection of spin current at the antiferromagnetic interface. Previously, efficient spin injection at these interfaces was realized at cryogenic temperatures. 

Researchers from FLEET at Australia's RMIT University, South China University of Technology and the Chinese Academy of Sciences (CAS) have observed electric gate-controlled exchange-bias effect in van der Waals heterostructures. The team describes this as “a promising platform for future energy-efficient, beyond-CMOS electronics”.

The exchange-bias (EB) effect, which originates from interlayer magnetic coupling, has played a significant role in fundamental magnetics and spintronics since its discovery. Although manipulating the EB effect by an electronic gate has been a significant goal in spintronics, until now, only very limited electrically-tunable EB effects have been demonstrated.