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

Researchers use a multiferroic magnetoelectric material to electrically control spin currents

A research team, led by the University of California, Berkeley, recently took a step toward a spin-based computer by demonstrating a way to switch spin currents on and off electrically.

The development of devices based on pure spin currents instead of charge currents is the goal of many scientists working in spin electronics, or spintronics. A subfield of spintronics, called magnonics, focuses on devices in which these spin currents are carried specifically by magnons—wave-like disturbances of the aligned spins in a magnetic material. Magnonics researchers face a challenge in that simply exciting magnons in a material is not enough to guarantee the creation of a spin current: when the magnons are uniformly distributed, the spin current is exactly equal to zero. The magnons must be controlled, and controlling magnons in insulating materials—ones that, because of the absence of charge currents, dissipate the least amount of energy—has proven difficult. In previous experiments, researchers have sought to achieve this control using large magnetic fields, but such fields can cause collateral heating, undermining the reason for pursuing magnonics in the first place.

Read the full story Posted: Aug 16,2022

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”.

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 demonstrate spiral spin liquid on a van der Waals honeycomb magnet

Researchers at Oak Ridge National Laboratory (ORNL) have used neutron scattering to show that a spiral spin liquid is realized in the van der Waals honeycomb magnet iron trichloride (FeCl3). The ORNL team grew the host material and demonstrated this long-predicted behavior.

The team's work demonstrates that spiral spin liquids can be achieved in two-dimensional systems and provides a promising platform to study the fracton physics in spiral spin liquids. 

Read the full story Posted: Jul 29,2022

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 take a step towards controlling electron spin at room temperature

Scientists have long since been trying to use electric fields to control spin at room temperature but achieving effective control has thus far been elusive. In a recent research work, a team from Rensselaer Polytechnic Institute and the University of California at Santa Cruz took a step forward in addressing the issue.

An electron has a spin degree of freedom, meaning that it not only holds a charge but also acts like a little magnet. In spintronics, a key task is to use an electric field to control electron spin and rotate the north pole of the magnet in any given direction. The spintronic field effect transistor harnesses the so-called Rashba or Dresselhaus spin-orbit coupling effect, which suggests that one can control electron spin by electric field. Although the method holds promise for efficient and high-speed computing, certain challenges must be overcome before the technology reaches its true, miniature but powerful, and eco-friendly, potential.

Read the full story Posted: Jul 15,2022

Researchers explore spin manipulation technique as a path towards ultralow power electronics

Researchers from Beihang University and University of British Columbia have found that spin flipping can be achieved by the valley-Zeeman SOF in monolayer tungsten diselenide (WSe2) at room temperature, which manifests as a negative magnetoresistance in the vertical spin valve.

Manipulating spins can enable the development of ultralow power electronics, but previous approaches were limited by the strength of the effective field and high-quality structures. The team in this recent study explored a mechanism to manipulate spins at room temperature with monolayer tungsten diselenide, in virtue of a novel giant spin-orbit field.

Read the full story Posted: Jul 14,2022

Researchers develop new multiferroic heterostructure material with the highest spintronic performance in the world

A joint research group that included scientists from Osaka University, Tokyo Institute of Technology and University of York has achieved what is reportedly the world's highest level performance index (magnetic electrical coupling coefficient) in developing a high-performance interfacial multiferroic structure for new voltage information writing technology in spintronics devices. At the same time, they successfully demonstrated repeated switching of nonvolatile memory states by applying an electric field.

A challenge for magnetoresistive memory (MRAM), which is expected to become the next-generation of nonvolatile memory devices, is that it consumes a large amount of power because current is passed through its metallic magnetic material when information is written. The research group has demonstrated a high-performance interfacial multiferroic structure consisting of a high-performance metallic magnetic material and a piezoelectric material bonded together using their own technology, and developed a technology to switch the magnetization direction of the metallic magnetic material efficiently by simply applying voltage instead of an electric current.

Read the full story Posted: Jul 12,2022

Researchers examine the prospects of 2D materials for non-volatile spintronic memories

A new study, coordinated by ICN2 group leaders and ICREA professors Prof. Stephan Roche and Prof. Sergio O. Valenzuela, and by Prof. Hyunsoo Yang from the National University of Singapore, examined the current developments and challenges in regards to MRAM, and outlined the opportunities that can arise by incorporating two-dimensional material technologies. It highlighted the fundamental properties of atomically smooth interfaces, the reduced material intermixing, the crystal symmetries and the proximity effects as the key drivers for possible disruptive improvements for MRAM at advanced technology nodes.

The research was carried out by a collaboration of various members of the Graphene Flagship project consortium, including various institutes of the Centre national de la recherche scientifique (CNRS, France), Imec (Belgium), Thales Research and Technology (France), and the French Atomic Energy Commission (CEA), as well as key industries such as Samsung Electronics (South Korea) and Global Foundries (Singapore).

Read the full story Posted: Jun 28,2022

Researchers develop method to obtain in-depth and time-resolved view on magnetization

Researchers in Germany, led by the Max Born Institute, have developed a novel technique to obtain “in depth” and time-resolved view on magnetization, employing broadband femtosecond soft X-ray pulses to study the transient evolution of magnetization depth profiles within a magnetic thin film system. This is vital as the future development of functional magnetic devices based on ultrafast optical manipulation of spins requires an understanding of the depth-dependent spin dynamics across the interfaces of complex magnetic heterostructures.

In current information technology, functional magnetic devices typically consist of stacks of thin layers of magnetic and nonmagnetic materials, each only about one nanometer thick. The stacking, choice of atomic species, and the resulting interfaces between the layers are key to the particular function, for example as realized in the giant magnetoresistance read heads in all magnetic hard drives. Over the last years, it was shown that ultrashort laser pulses down to the femtosecond range (1 femtosecond = 10-15 s) can effectively and very fast manipulate the magnetization in a material, allowing a transient change or even permanent reversal of the magnetization state. While these effects have been predominantly studied in simple model systems, future applications will require an understanding of magnetization dynamics in more complex structures with nanometer-scale heterogeneity.

Read the full story Posted: Jun 23,2022