July 2022

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 (FeCl_3). 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. 

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.

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.

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.

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.