January 2022

Researchers from Japan Advanced Institute of Science and Technology (JAIST), Kyoto University and the National Institute for Materials Science in Japan have detected energetic magnons in yttrium iron garnet (YIG), a magnetic insulator, by using a quantum sensor based on diamond with NV centers.

Nitrogen-vacancy (N-V) centers in diamond, basically a point defect consisting of a nitrogen atom paired with an adjacent lattice vacancy, have emerged as a key for high-resolution quantum sensors. It has been demonstrated that N-V centers can detect coherent magnon. However, detecting the thermally excited magnons by heat using N-V centers is difficult since the thermal magnons have much higher energy than the spin state of N-V centers, limiting their interaction.

An international team of researchers, led by the National Research Council (CNR), IOM institute in Trieste, Italy, and the Departments of Chemistry at Princeton University, Louisiana State University and Rutgers University in United States, has relied in a joint venture between theorists, experimentalists and sample growers across chemistry and physics to study the magnetic and electronic properties of EuSn₂P₂, a magnetic topological insulator composed of Europium, Tin, and Phosphorus arranged in a layer-by-layer crystalline structure.

The understanding and the interplay of magnetism and high-order topology in a quantum material is one of the most challenging research directions in materials science, holding potentialities for future spintronics applications, where the spin carried by an electron, being an essential quantum entity, could be manipulated and used as information carrier in a device and/or as a single quantum bit of information.

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.