A team of researchers from the DOE/Argonne National Laboratory and U.S. additional laboratories and universities have reported a mechanical response across a layered magnetic material tied to changing its electron spin. This response could have important applications in nanodevices requiring ultra-precise and fast motion control.

A little over a century ago, physicists Albert Einstein and Wander de Haas reported a surprising effect in ferromagnets: if you suspend an iron cylinder from a wire and expose it to a magnetic field, it will start rotating if you simply reverse the direction of the magnetic field. "Einstein and de Haas's experiment is almost like a magic show," said Haidan Wen, a physicist in the Materials Science and X-ray Science divisions of the U.S. Department of Energy's (DOE) Argonne National Laboratory. ​"You can cause a cylinder to rotate without ever touching it."

A team of scientists from the University of Minnesota Twin Cities has synthesized a thin film of a unique topological semimetal material that has the potential to generate more computing power and memory storage while using significantly less energy. The researchers were also able to closely study the material, leading to some fascinating findings about the physics behind its unique properties.

Much attention is put into developing the materials that power electronic devices. While traditional semiconductors are the technology behind most of today's computer chips, scientists are always looking for new materials that can generate more power with less energy to make electronics better, smaller, and more efficient. One such candidate for these new and improved computer chips is a class of quantum materials called topological semimetals. The electrons in these materials behave in different ways, giving the materials unique properties that typical insulators and metals used in electronic devices do not have. For this reason, they are being explored for use in spintronic devices, an alternative to traditional semiconductor devices that leverage the spin of electrons rather than the electrical charge to store data and process information.

Researchers from the Hebrew University of Jerusalem in Israel have made a recent discovery that could change the face of spintronics research.

A spintronics device developed by Professor Capua's lab

They discovered that the most important equation used to describe magnetization dynamics, namely the Landau-Lifshitz-Gilbert (LLG) equation, also applies to the optical domain. Consequently, they found that the helicity-dependent optical control of the magnetization state emerges naturally from their calculations. This is a very surprising result since the LLG equation was considered to describe much slower dynamics and it was not expected to yield a meaningful outcome also at the optical limit.

Researchers from Purdue University, Pennsylvania State University and Japan's National Institute for Materials Science (NIMS) have reported electrically tunable moiré magnetism in twisted double bilayers (a bilayer on top of a bilayer with a twist angle between them) of layered antiferromagnet chromium triiodide. 

Using magneto-optical Kerr effect microscopy, the team observed the coexistence of antiferromagnetic and ferromagnetic order with non-zero net magnetization—a hallmark of moiré magnetism. Such a magnetic state extends over a wide range of twist angles (with transitions at around 0° and above 20°) and exhibits a non-monotonic temperature dependence. The researchers also demonstrated voltage-assisted magnetic switching. The observed non-trivial magnetic states, as well as control via twist angle, temperature and electrical gating, are supported by a simulated phase diagram of moiré magnetism.

Researchers from the Chinese Academy of Sciences (CAS) and the University of Science and Technology of China have demonstrated considerable control of magnetism at low electric fields (E) at room temperature. The E-induced phase transformation and lattice distortion were found to lead to the E control of magnetism in multiferroic BiFeO₃-based solid solutions near the morphotropic phase boundary (MPB). 

Multiferroic materials, with magnetic and ferroelectric properties, are promising for multifunctional memory devices. Magnetoelectric-based control methods in insulating multiferroic materials require less energy and have potential for high-speed, low-power information storage applications. BiFeO₃ is a room-temperature multiferroic material with potential for use in spintronics devices, but its weak ferromagnetic and magnetoelectric effects and high voltage required for manipulation are weaknesses. In their recent study, the researchers grew single crystals of the multiferroic 0.58BiFeO₃-0.42Bi_0.5K_0.5TiO₃ (BF-BKT), which lies in the tetragonal region adjacent to the MPB.

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 Korea Research Institute of Standards and Science (KRISS), Konkuk University, Ulsan National Institute of Science and Technology (UNIST) and Pusan National University have pioneered the world's first transistor capable of controlling skyrmions. This breakthrough paves the way for the development of next-generation ultra-low-power devices and is anticipated to make significant contributions to quantum and AI research. 

Skyrmions, arranged in a vortex-like spin structure, are unique because they can be miniaturized to several nanometers, making them movable with exceptionally low power. This characteristic positions them as a crucial element in the evolution of spintronics applications.

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. 

The discovery of new quantum materials with magnetic properties could pave the way for ultra-fast and considerably more energy-efficient computers and mobile devices. So far, however, these types of materials have been shown to work only at extremely cold temperatures. Now, for the first time, a research team at Chalmers University of Technology, Lund University and Uppsala University in Sweden has created a two-dimensional (2D) magnetic quantum material that works at room temperature.

Today’s rapid expansion of information technology (IT) is generating massive amounts of digital data that needs to be stored, processed and communicated. This requires energy, and IT is projected to account for over 30% of the world’s total energy consumption by 2050. To solve this problem, the research community is entering a new paradigm in materials science. The research and development of 2D quantum materials is opening new doors for sustainable, faster and more energy-efficient data storage and processing in computers and mobiles.

Researchers at the Max Born Institute in Germany recently discovered a method for inducing and controlling the flow of spin and valley currents in ultrafast timeframes, using specially designed laser pulses. This discovery could offer a novel perspective on the search for the next generation of information technologies.

Ultrafast laser control over the basic quantum properties of matter is a critical challenge that must be addressed to develop future information technologies beyond the semiconductor electronics that define our current era. Electron spin and valley index, an emergent property of two-dimensional materials related to quasiparticle momentum, are two promising quantum properties in this regard. Both spintronics and valleytronics offer many potential advantages over classical electronics in terms of data manipulation speed and energy efficiency. While spin excitations suffer from a dynamic loss of character due to spin-orbit-induced spin precession, the valley wavefunction represents a more stable "data bit" that is only threatened by intervalley scattering, a feature controllable by sample quality. Valleytronics thus presents a potentially robust platform for moving beyond classical electronics.