Spin-orbit–driven ferromagnetism detected in 'magic-angle' twisted bilayer graphene

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."

Novel semiconductor sheds new light on Anomalous Hall Effect

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 succeed in measuring the properties of spin waves in graphene

Researchers from Harvard University and Japan's National Institute for Materials Science have demonstrated a new way to measure the properties of spin waves in graphene.

New method to measure spin waves in graphene imageA charge sensor measuring the cost of electrons surfing on the spin wave (green wavy lines) (Credit: Yacoby Lab/ Harvard SEAS)

Spin waves, a change in electron spin that propagates through a material, could fundamentally change how devices store and carry information. These waves, also known as magnons, don’t scatter or couple with other particles. Under the right conditions, they can even act like a superfluid, moving through a material with zero energy loss.

Researchers combine two cognitive computing nano-elements into one

Researchers at Tohoku University and the University of Gothenburg have designed a new spintronics technology for brain-inspired computing.

Sophisticated cognitive tasks, such as image and speech recognition, have seen recent breakthroughs thanks to deep learning. Even so, the human brain still executes these tasks without exerting much energy and with greater efficiency than any computer. The development of energy-efficient artificial neurons capable of emulating brain-inspired processes has therefore been a major research goal for decades.

Researchers design a system that demonstrates unusually long-range Josephson coupling across a half-metallic ferromagnet

An international team has, for the first time, designed a material system that exhibits an unusually long-range Josephson effect. Regions of superconducting YBa2Cu3O7 are separated by a region of half-metallic, ferromagnetic manganite (La2/3Sr1/3MnO3) one micron wide.

When two superconducting regions are separated by a strip of non-superconducting material, a special quantum effect can occur, coupling both regions. This is known as the Josephson effect. If the spacer material is a half-metal ferromagnet, it can open up new potential applications for novel spintronic applications.

Researchers find new topological magnet with colossal angular magnetoresistance

A research team led by Prof. Kim Jun Sung in the Center for Artificial Low Dimensional Electron Systems within the Institute for Basic Science (IBS, South Korea) and Physics Department at Pohang University of Science and Technology (POSTECH, South Korea) has found a new magnetotransport phenomenon, in the magnetic semiconductor Mn3Si2Te6. The group found that the magnitude of change in resistance can reach as much as a billion-fold under a rotating magnetic field. This unprecedented shift of resistance depending on magnetic field angle is called colossal angular magnetoresistance (CAMR).

A key challenge in spintronics is finding an efficient and sensitive way to electrically detect the electronic spin state. For example, the discovery of giant magnetoresistance (GMR) in the late 1980s, allowed for such functionality. In GMR, a large change in electrical resistance occurs under the magnetic field depending on parallel or antiparallel spin configurations of the ferromagnetic bilayer. The discovery of GMR has led to the development of hard-disk drive technology, which is technically the first-ever mass-produced spintronic device. Since then, discoveries of other related phenomena, including colossal magnetoresistance (CMR) which occurs in the presence of a magnetic field, have advanced our understanding of the interplay between spin and charge degrees of freedom and served as a foundation of emergent spintronic applications.

Researchers demonstrate non-volatile control of spin-to-charge conversion in germanium telluride

A team of researchers at Politecnico di Milano, University Grenoble Alpes and other institutes worldwide have recently demonstrated the non-volatile control of the spin-to-charge conversion in germanium telluride, a known Rashba semiconductor, at room temperature. Their work could have important implications for the future development of spintronic devices.

The Rashba effect, discovered in 1959, entails a momentum-independent splitting of spin bands in two-dimensional condensed matter systems. In ferroelectric Rashba semiconductors, this effect can be reversed by switching the direction of the ferroelectric polarization. The idea that Rashba spin-splitting in these materials can be controlled was confirmed by a series of first-principle calculations by S. Picozzi and later validated in spectroscopic experiments using germanium telluride, which is thus often considered the 'prototype' of the ferroelectric Rashba class of semiconductors.

Scientists develop thin-film membrane that demonstrates an intrinsic coupling between voltage and spin

Scientists at the University of Wisconsin-Madison have developed an all-thin-film membrane composite of the relaxor-ferroelectric material lead magnesium niobate-lead titanate (PMN-PT) and ferromagnetic nickel that demonstrates an intrinsic coupling between voltage and spin.

When they apply voltage to the structure, it rotates the spins of the nickel layer, a magnetoelectric effect important for spintronics. The extreme thinness of the structure allows the use of low-voltages.

Researchers launch new paradigm in magnetism and superconductivity

An international team of scientists from Austria and Germany has launched a new paradigm in magnetism and superconductivity, highlighting the effects of curvature, topology, and 3D geometry.

In modern magnetism, superconductivity and spintronics, extending nanostructures into the third dimension has become a major research avenue because of geometry-, curvature- and topology-induced phenomena. This approach provides a means to improve this and to launch novel functionalities by tailoring the curvature and 3D shape.

Lead-Vacancy Centers in Diamonds could benefit spintronics

Researchers from Japan's Tokyo Institute of Technology, National Institute for Materials Science and National Institute of Advanced Industrial Science and Technology have found that lead-based vacancy centers in diamonds, that form after high-pressure and high-temperature treatment, are ideal for quantum networks, spintronics and quantum sensors.

The color in a diamond comes from a defect, or “vacancy,” where there is a missing carbon atom in the crystal lattice. Vacancies have long been of interest to electronics researchers because they can be used as ‘quantum nodes’ or points that make up a quantum network for the transfer of data. One of the ways of introducing a defect into a diamond is by implanting it with other elements, like nitrogen, silicon, or tin. In their recent study, the scientists from Japan demonstrated that lead-vacancy centers in diamond have the right properties to function as quantum nodes. “The use of a heavy group IV atom like lead is a simple strategy to realize superior spin properties at increased temperatures, but previous studies have not been consistent in determining the optical properties of lead-vacancy centers accurately,” says Associate Professor Takayuki Iwasaki of Tokyo Institute of Technology (Tokyo Tech), who led the study.