Ferromagnetism

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 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 at Cornell University and University of Nebraska have discovered a strategy to switch the magnetization in thin layers of a ferromagnet. This a technique has the potential to lead to the development of more energy-efficient magnetic memory devices.

Scientists have been trying for many years to change the orientation of electron spins in magnetic materials by manipulating them with magnetic fields. But researchers including Dan Ralph, the F.R. Newman Professor of Physics in the College of Arts and Sciences and the paper's senior author, have instead looked to using spin currents carried by electrons, which exist when electrons have spins generally oriented in one direction.

Scientists from MIT, Arizona State University, National Institute for Materials Science in Tsukuba, Université de Liège in Belgium and Italy's CNR-SPIN have discovered an exotic "multiferroic" state in a material that is as thin as a single layer of atoms.

Their observation is the first to confirm that multiferroic properties can exist in a perfectly two-dimensional material. The findings could pave the way for developing smaller, faster, and more efficient data-storage devices built with ultrathin multiferroic bits, as well as other new nanoscale structures.

A research team from Brown University has found a surprising new phenomenon that can arise in 'magic-angle graphene' - two sheets of graphene that are stacked together at a particular angle with respect to each other, giving rise to various fascinating behaviors. In a recent research, the team showed that by inducing a phenomenon known as spin-orbit coupling, magic-angle graphene becomes a powerful ferromagnet.

"Magnetism and superconductivity are usually at opposite ends of the spectrum in condensed matter physics, and it's rare for them to appear in the same material platform," said Jia Li, an assistant professor of physics at Brown and senior author of the research. "Yet we've shown that we can create magnetism in a system that originally hosts superconductivity. This gives us a new way to study the interplay between superconductivity and magnetism, and provides exciting new possibilities for quantum science research."

Researchers at Tokyo Institute of Technology, the University of Tokyo, Japan Science and Technology Agency (JST), RIKEN and Comprehensive Research Organization for Science and Society (CROSS) have demonstrated a large, unconventional anomalous Hall resistance in a new magnetic semiconductor in the absence of large-scale magnetic ordering.

This validates a recent theoretical prediction and provides new insights into the anomalous Hall effect, a quantum phenomenon that has previously been associated with long-range magnetic order.

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.

The attractive properties of Sr₂RuO₄, like its ability to carry lossless electrical currents and magnetic information simultaneously, make it a material with great potential for the development of future technologies like superconducting spintronics and quantum electronics. An international research team, led by scientists at the University of Konstanz, was recently able to answer one of the most interesting open questions on Sr₂RuO₄: why does the superconducting state of this material exhibit some features that are typically found in materials known as ferromagnets, which are considered being antagonists to superconductors?

Spin polarized muon particles (red spheres with arrows) probing a new form of magnetism in the perovskite superconductor Sr2RuO4. Credit: Konstanz University

The team has found that the material hosts a new form of magnetism, which can coexist with superconductivity and exists independently of superconductivity as well.

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.

Researchers from Berkeley Lab, UC Berkeley, UC Riverside, Argonne National Laboratory, Nanjing University and the University of Electronic Science and Technology of China, have developed an ultrathin magnet that operates at room temperature. This development could lead to new applications in computing and electronics - such as high-density, compact spintronic memory devices - and new tools for the study of quantum physics.

"We're the first to make a room-temperature 2D magnet that is chemically stable under ambient conditions," said senior author Jie Yao, a faculty scientist in Berkeley Lab's Materials Sciences Division and associate professor of materials science and engineering at UC Berkeley. "This discovery is exciting because it not only makes 2D magnetism possible at room temperature, but it also uncovers a new mechanism to realize 2D magnetic materials," added Rui Chen, a UC Berkeley graduate student in the Yao Research Group and lead author on the study.