Antiferromagnetism

Researchers manage to achieve room temperature functionality of antiferromagnetic hybrids

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. 

Read the full story Posted: Aug 24,2022

Manipulating interlayer magnetic coupling in vdW heterostructures

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”.

 a solid-proton field-effect transistor (SP-FET) mounts the AFM-FM heterostructure within electric contact (gold), mounted on a solid protonic conductor (SPC) and gate electrode (Pt) image

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.

Read the full story Posted: Aug 09,2022

Researchers report milestone for antiferromagnetic spintronics

Researchers from the University of Tokyo and CREST (Japan Science and Technology Agency) have explored the world of spintronics and other related areas of solid state physics with a focus on antiferromagnets. The team has reported, in its recent study, the experimental realization of perpendicular and full spin–orbit torque switching of an antiferromagnetic binary state.

The team used the chiral antiferromagnet Mn3Sn, which exhibits the magnetization-free anomalous Hall effect owing to a ferroic order of a cluster magnetic octupole hosted in its chiral antiferromagnetic state. They fabricated heavy-metal/Mn3Sn heterostructures by molecular beam epitaxy and introduce perpendicular magnetic anisotropy of the octupole using an epitaxial in-plane tensile strain. By using the anomalous Hall effect as the readout, the team demonstrated 100% switching of the perpendicular octupole polarization in a 30-nanometre-thick Mn3Sn film with a small critical current density of less than 15 megaamperes per square centimeter. Their theory is that the perpendicular geometry between the polarization directions of current-induced spin accumulation and of the octupole persistently maximizes the spin–orbit torque efficiency during the deterministic bidirectional switching process. The team's recent work provides a significant basis for antiferromagnetic spintronics.

Read the full story Posted: Jul 21,2022

Researchers spot spin swapping in an antiferromagnet

Researchers at Johns Hopkins University, University of Texas at Austin, Northeastern University and Argonne National Laboratory have reported a new quantum phenomenon in antiferromagnetic insulators that could open the door to new ways of powering  spintronic devices.

Antiferromagnetic insulators are advantageous in spintronic applications because of their low stray fields and rapid magnetic dynamics. Controlling their magnetization and reading their magnetic state is critical for these applications, but they are challenging.

Read the full story Posted: May 23,2022

Control of Bistable Antiferromagnetic States for Spintronics

Scientists from MPI CPfS, in collaboration with colleagues from National Yang Ming Chiao Tung University, National Cheng Kung University, and National Synchrotron Radiation Research Center in Taiwan as well as from Hiroshima University in Japan, have used strained engineering on multiferroic BiFeO3 (BFO) thin films, to fabricate bistable antiferromagnetic states at room temperature for the first time.

These two antiferromagnetic states are non-volatile and very close to each other in energy, which was verified by soft x-ray linear dichroism spectroscopy. Moreover, these two non-volatile antiferromagnetic states can be reversibly switched by a moderate magnetic field and a non-contact optical approach. The team stressed that the conductivity of the two antiferromagnetic domains is drastically different.

Read the full story Posted: May 02,2022

Researchers discover new Fermi arcs that could be the future of spintronics

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.

Read the full story Posted: Apr 02,2022

Researchers estimate that 4f antiferromagnets could push spintronics applications forward

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.

Read the full story Posted: Mar 01,2022

Stacking order in a 2D magnet produces Dirac magnons

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.

Read the full story Posted: Nov 14,2021

Researchers demonstrate programmable dynamics of exchange-biased domain wall via spin-current-induced antiferromagnet switching

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.

Read the full story Posted: Aug 11,2021

Gate-controlled magnetic phase transition in a van der Waals magnet

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.

Read the full story Posted: Jun 29,2021