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Orbital currents are the lesser-known cousins of spin currents. Both involve an alignment of angular momentum. But spin currents are carried by spin-polarized electrons, while orbital currents are carried by electrons in orbitals having the same angular momentum. Like their spin counterparts, orbital currents could be useful for transmitting information in so-called orbitronic devices, but researchers had expected that these currents would not travel well across material interfaces. Now Igor Lyalin and Roland Kawakami from Ohio State University have measured the flow of orbital currents across selected materials placed in multilayer structures. They find, surprisingly, that the transport of orbital currents is as good or better than the transport of spin currents for most of the sampled materials.

Orbital currents can be generated via the so-called orbital Hall effect—a surface magnetization effect that was predicted 20 years ago but directly detected only in 2023 (see Synopsis: Detection of the Orbital Hall Effect). Interest in orbital currents is growing, as they could be more effective than spin currents at switching the orientation of magnetic layers in data-storage devices.

To study orbital current transport, Lyalin and Kawakami fabricated structures consisting of chromium and nickel layers, separated by a thin spacer. For the spacer material, they tested nonmagnetic metals, ferromagnetic metals, and antiferromagnetic insulators. The researchers generated an orbital current by applying a voltage to the chromium layer, and they measured how much of this current flowed through the structures by observing a magnetization change in the nickel. They found that 12 of the 15 spacer materials transported orbital currents more efficiently than spin currents—a result that could be good news for developing future orbitronic devices, Kawakami says.

A simple light microscopy setup can map the micrometer-scale domains of a potentially useful class of magnetic materials.

Ultraviolet photons induce potassium niobate to behave like a potent solid-state refrigerant, according to new calculations.

Claudio Cazorla of the Polytechnic University of Catalonia in Spain and his collaborators have used a suite of numerical methods to discover that the archetypal ferroelectric material, potassium niobate (KNO), also exhibits a photocaloric effect: In response to ultraviolet light, KNO reversibly absorbs heat [1]. Because the effect is large and works at a wide range of temperatures, including room temperature, KNO could serve as the working medium for new cooling devices.

KNO owes its ferroelectric and photocaloric effects to its perovskite crystal structure, which features a niobium ion surrounded by an octahedral cage of oxygen ions. At low temperatures, the niobium ion is offset from the cage’s center, which induces an electric polarization (the ferroelectric effect). Above 700 K, KNO adopts a nonpolar configuration as its most stable phase.

Researchers from Monash University, part of the FLEET Center, have revealed a generic approach towards intrinsic magnetic second-order topological insulators. These materials are crucial for advancements in spintronics, an emerging field aiming at using spin degree of freedom to deliver information. Their study is published in Nano Letters.

A new software package developed by researchers at Macquarie University can accurately model the way waves—sound, water or light—are scattered when they meet complex configurations of particles.

In polymers, the competition between the folding and aggregation of chains, both at an individual level and between chains, can determine the mechanical, thermal, and conductive properties of such materials. Understanding the interplay of folding and aggregation presents a significant opportunity for the development and discovery of polymeric materials with tailored properties and functionalities.

Yet, the current flow along these topologically protected, one-dimensional edges has proven to be far from robust. With the QAHE breaking down in magnetically doped topological insulators at temperatures higher than 1 Kelvin, well below the temperatures predicted by theory.

A new class of materials, known as intrinsic magnetic topological insulators (MTIs), for example MnBi₂Te₄, possess both non-trivial topology and intrinsic magnetism and are predicted to offer more robust QAHE at higher temperatures than magnetically doped topological insulators.

In MnBi₂Te₄ it has been shown that the QAHE can survive up to 1.4 K, and interestingly, this can rise to 6.5 K with the application of stabilizing magnetic fields, providing hints at the mechanisms that are driving the breakdown of topological protection.

In conjunction with research staff from the Charles University of Prague and the CFM (CSIC-UPV/EHU) center in San Sebastian, CIC nanoGUNE’s Nanodevices group has designed a new complex material with emerging properties in the field of spintronics. This discovery, published in the journal Nature Materials, opens up a range of fresh possibilities for the development of novel, more efficient and more advanced electronic devices, such as those that integrate magnetic memories into processors.

Building a robot takes time, technical skill, the right materials – and sometimes, a little fungus.

In creating a pair of new robots, Cornell researchers cultivated an unlikely component, one found not in the lab but on the forest floor: fungal mycelia. By harnessing mycelia’s innate electrical signals, the researchers discovered a new way of controlling “biohybrid” robots that can potentially react to their environment better than their purely synthetic counterparts.

The team’s paper, “Sensorimotor Control of Robots Mediated by Electrophysiological Measurements of Fungal Mycelia,” published Aug. 28 in Science Robotics. The lead author is Anand Mishra, a research associate in the Organic Robotics Lab led by Rob Shepherd, professor of mechanical and aerospace engineering in Cornell Engineering, and the paper’s senior author.