April 2024

Spins can form complex magnetic structures within the nanometer and micrometer scale in which the magnetization direction twists along specific directions. Examples of such structures are magnetic bubbles, skyrmions, and magnetic vortices. Spintronics aims to make use of such tiny magnetic structures to store data or perform logic operations with very low power consumption compared to today's dominant microelectronic components. However, the generation and stabilization of most of these magnetic textures is restricted to a few materials and achievable under very specific conditions (temperature, magnetic field, etc.).

An international collaboration led by Helmholtz-Zentrum Berlin (HZB) has presented a new approach that can be used to create and stabilize complex spin textures, such as radial vortices, in a variety of compounds. In a radial vortex, the magnetization points towards or away from the center of the structure. This type of magnetic configuration is usually highly unstable. Within this novel approach, radial vortices are created with the help of superconducting structures, while the presence of surface defects achieves their stabilization.

Researchers at Japan's National Institute for Materials Science have developed an improved type of microscope that can visualize key aspects of electron spin states in materials. The quantum mechanical property of electrons called spin is more complex than the spin of objects in our everyday world but is related to it as a measure of an electron’s angular momentum. The spin states of electrons can have a significant impact on the electronic and magnetic behavior of the materials they are part of.

The technology, developed by Koichiro Yaji and Shunsuke Tsuda, is known as imaging-type spin-resolved photoemission microscopy (iSPEM). It uses the interaction of light with the electrons in a material to detect the relative alignment of the electron spins. It is particularly focused on electron spin polarization – the extent to which electron spins are collectively aligned in a specific direction.

Researchers at MIT have tackled key obstacles to bringing 2D magnetic materials into practical use. The team designed a “van der Waals atomically layered heterostructure” device where a 2D van der Waals magnet, iron gallium telluride, is interfaced with another 2D material, tungsten ditelluride. The team shows that the magnet can be toggled between the 0 and 1 states simply by applying pulses of electrical current across their two-layer device. 

Use of magnetic materials to build computing devices like memories and processors has emerged as a promising avenue for creating “beyond-CMOS” computers, which would use far less energy compared to traditional computers. Magnetization switching in magnets can be used in computation the same way that a transistor switches from open or closed to represent the 0s and 1s of binary code. While much of the research along this direction has focused on using bulk magnetic materials, a new class of magnetic materials — called two-dimensional van der Waals magnets — provides superior properties that can improve the scalability and energy efficiency of magnetic devices to make them commercially viable.

Researchers from Johannes Gutenberg-University Mainz, ALBA Synchrotron Light Facility and Tohoku University have identified quasiparticles called merons in a synthetic antiferromagnet for the first time, which could lead to new concepts for spintronics devices.

The spintronics field is still rather nascent as research is ongoing. Recent research has focused on structures called skyrmions as potential building blocks. These structures are quasiparticles made up of numerous electron spins and can be thought of as two-dimensional whirls (or “spin textures”) within a material. Skyrmions exist in many magnetic materials, including cobalt–iron–silicon and the manganese–silicide thin films in which they were first discovered. They are attractive spintronics candidates because they are robust to external perturbations, making them particularly stable for storing and processing the information they contain. At just tens of nanometres across, they are also much smaller than the magnetic domains used to encode data in today’s disk drives, making them ideal for future data storage technologies such as “racetrack” memories. Like skyrmions, merons are made up of numerous individual spins. Unlike them, their stray magnetic fields are miniscule, which would facilitate ultrafast operations and even higher information storage densities within a device. Until now, however, merons have only been observed in natural antiferromagnets, where they have proved difficult to analyze and manipulate.