Merons realized in synthetic antiferromagnets

Direct observation of antiferromagnetic merons and antimerons
Illustration Credit: Mona Bhukta

Researchers in Germany and Japan have been able for the first time to identify collective topological spin structures called merons in layered synthetic antiferromagnets

The electronic devices we use on a day-to-day basis are powered by electrical currents. This is the case with our living room lights, washing machines, and televisions, to name but a few examples. Data processing in computers also relies on information provided by tiny charge carriers called electrons. The field of spintronics, however, employs a different concept. Instead of the charge of electrons, the spintronic approach is to exploit their magnetic moment, in other words, their spin, to store and process information – aiming to make the computers of the future more compact, fast, and sustainable. One way of processing information based on this approach is to use the magnetic vortices called skyrmions or, alternatively, their still little understood and rarer cousins called 'merons'. Both are collective topological structures formed of numerous individual spins. Merons have to date only been observed in natural antiferromagnets, where they are difficult to both analyze and manipulate.

New quantum entangled material could pave way for ultrathin quantum technologies

Artistic illustration depicts heavy-fermion Kondo matter in a monolayer material.
Illustration Credit: Adolfo Fumega/Aalto University

Researchers reveal the microscopic nature of the quantum entangled state of a new monolayer van der Waals material

Two-dimensional quantum materials provide a unique platform for new quantum technologies, because they offer the flexibility of combining different monolayers featuring radically distinct quantum states. Different two-dimensional materials can provide building blocks with features like superconductivity, magnetism, and topological matter. But so far, creating a monolayer of heavy-fermion Kondo matter – a state of matter dominated by quantum entanglement – has eluded scientists. Now, researchers at Aalto University have shown that it’s theoretically possible for heavy-fermion Kondo matter to appear in a monolayer material, and they’ve described the microscopic interactions that produces its unconventional behavior. These findings were published in Nano Letters.

“Heavy-fermion materials are promising candidates to discover unconventional topological superconductivity, a potential building block for quantum computers robust to noise,” says Adolfo Fumega, the first author of the paper and a post-doctoral researcher at Aalto University.

These materials can feature two phases: one analogous to a conventional magnet, and one where the state of the system is dominated by quantum entanglement, known as the heavy-fermion Kondo state. At the transition between the magnetic phase and the heavy-fermion state, macroscopic quantum fluctuations appear, leading to exotic states of matter including unconventional superconducting phases.

Out of the desert, a quantum powerhouse rises

Postdoctoral researcher Caitlin McCowan inspects pieces of silicon at the atomic level. She uses a scanning tunneling microscope to spot imperfections as part of a quantum research project at Sandia National Laboratories.
Photo Credit: Craig Fritz

They knew it was an ambitious goal. But by the time they announced it in 2022, Sandia National Laboratories and The University of New Mexico — two of the state’s largest research institutions — had been working out their strategy for more than a year.

Their goal: transform the state into a global powerhouse in the emerging quantum technology market. Success would mean the arrival of tech companies and startups, jobs and investments — an economic resurgence for the southwestern state.

The plan is picking up steam.

In January, Sandia and UNM created the Quantum New Mexico Institute, a cooperatively run research center headquartered at the university. This marks a major milestone in the comprehensive strategy to advance research, court businesses and train a quantum-ready workforce.

“Our vision is to make New Mexico a destination for quantum companies and scientists across the world,” said Setso Metodi, institute co-director and Sandia manager of quantum computer science.

‘Janitors’ of the Sea: Overharvested Sea Cucumbers Play Crucial Role in Protecting Coral

Photo Credit: Cody Clements

Corals are foundational for ocean life. Known as the rainforests of the sea, they create habitats for 25% of all marine organisms, despite only covering less than 1% of the ocean’s area. 

Coral patches the width and height of basketball arenas, used to be common throughout the world’s oceans. But due to numerous human-generated stresses and coral disease, which is known to be associated with ocean sediments, most of the world’s coral is gone.

“It’s like if all the pine trees in Georgia disappeared over a period of 30 to 40 years,” said Mark Hay, Regents’ Chair and the Harry and Anna Teasley Chair in Environmental Biology in the School of Biological Sciences at the Georgia Institute of Technology. “Just imagine how that affects biodiversity and ecosystems of the ocean.”

In first-of-its-kind research, Hay, along with research scientist Cody Clements, discovered a crucial missing element that plays a profound role in keeping coral healthy — an animal of overlooked importance known as a sea cucumber.

Study Offers Improved Look at Earth’s Ionosphere

Radio signal plasma wave from a parallel magnetic field. This animation shows the Faraday rotation phenomena in black. The grid at the end of the propagation path is the antenna, and the black line shows how the plane of polarization of the radio signal projects onto it.
Image Credit: E. Jensen/PSI.

New measuring techniques will enable improved measurements of the Earth’s ionosphere, a key to studying and reducing the impact of space weather.

Radio signals have been used to study the density of plasma since the 1920s. Transmitting radio sources include ground-based ionosondes (special radar for the examination of the ionosphere), astronomical phenomena such as pulsars and more recently spacecraft signals used for transmitting data. For example, Global Positioning Satellites (GPS) radio signals are used to measure the density of Earth’s ionosphere. However, the response of the radio signal to the ionospheric plasma is more complicated than simply varying as a function of density. The Earth’s magnetic field affects its electromagnetic wave fluctuations as well. For example, Faraday rotation is a well-known phenomenon, as shown in the image above. But, as a technique for measuring magnetic field, Faraday rotation is limited to just the portion that is oriented in the correct direction. Our discovery complements Faraday rotation enabling a complete measurement of magnetic field strength.

Modern hydropower plants also cause massive damage to ecology

Water samples collected by TUM researchers
Photo Credit: Lehrstuhl für Aquatische Systembiologie / TUM

Even modern and supposedly gentler hydropower plants cause considerable damage to river ecosystems. This is shown by a study by Prof. Jürgen Geist from the Chair of Aquatic Systems Biology at the TUM School of Life Sciences published in the Journal of Applied Ecology. Geist and his team investigated the changes in the complex biocoenoses in rivers at five locations in Bavaria before and after the installation of hydropower plants. They looked not only at fish but also at microorganisms, aquatic plants, and algae growth.

Significant differences in living conditions were observed at all locations, emphasizes Geist. This applies to the situation upstream and downstream of the power plants as well as before and after installation. "Contrary to what was hoped for and predicted by the operators, the new types of power plant have not improved the habitat conditions for current-loving species," the biologist states. In particular, retrofitting existing weirs in conjunction with further damming would have negative effects.

"When planning future plants, in addition to the question of the sometimes-considerable damage to fish when passing through hydropower plants, the previously neglected effects on the habitat and the food web must also be taken into account. This is about the ecological continuity and connection of different river sections as an important criterion for healthy river systems," said Geist. The requirements are defined in the EU Water Framework Directive.

Immune system meets cancer: Checkpoint identified to fight solid tumor

Immunofluorescence image of the expression of PHGDH (red) and CD3 T cells (green) in cryosectioned AE17 mesothelioma.
Image Credit: Zhengnan Cai

Checkpoint PHDGH in tumor-associated macrophages influences immune response and tumor growth

A study by a scientific team from the University of Vienna and the MedUni Vienna, recently published in the top-class journal Cellular & Molecular Immunology, has a promising result from tumor research: The enzyme phosphoglycerate dehydrogenase (PHDGH) acts as a metabolic checkpoint in the function of tumor-associated macrophages (TAMs) and thus on tumor growth. Targeting PHGDH to modulate the cancer-fighting immune system could be a new starting point in cancer treatment and improve the effectiveness of clinical immunotherapies.

Our immune system constantly fights emerging cancer cells that arise from mutations. This process is controlled, among other things, by different types of macrophages. Tumor-associated macrophages (TAMs) are among the most abundant immune cells in the tumor microenvironment. They come from tissue-resident immune cells circulating in the blood that penetrate the tumor and differentiate there in response to various messenger substances (cytokines) and growth factors. In most solid tumors, TAMs are paradoxically considered to be tumor-promoting ("protumorigenic") overall: they promote tumor growth and metastasis by suppressing the immune response, promoting the vascular supply to the tumor and also increasing resistance to drug therapies – i.e. they generally correlate with a poor prognosis for the affected patients. Previous attempts to influence TAMs proved unsatisfactory because many patients had only a limited response to these therapeutic approaches. This underlines the urgency of finding new active ingredients and strategies.

Gut-brain communication turned on its axis

How the gut communicates with the brain
Image Credit: Copilot AI

The mechanisms by which antidepressants and other emotion-focused medications work could be reconsidered due to an important new breakthrough in the understanding of how the gut communicates with the brain.

New research led by Flinders University has uncovered major developments in understanding how the gut communicates with the brain, which could have a profound impact on the make-up and use of medications such as antidepressants.

“The gut-brain axis consists of complex bidirectional neural communication pathway between the brain and the gut, which links emotional and cognitive centers of the brain,” says Professor Nick Spencer from the College of Medicine and Public Health.

“As part of the gut-brain axis, vagal sensory nerves relay a variety of signals from the gut to the brain that play an important role in mental health and wellbeing.

“The mechanisms by which vagal sensory nerve endings in the gut wall are activated has been a major mystery but remains of great interest to medical science and potential treatments for mental health and wellbeing.”

Human stem cells coaxed to mimic the very early central nervous system

Jianping Fu, Ph.D., Professor of Mechanical Engineering at the University of Michigan and the corresponding author of the paper being published at Nature discusses his team’s work in their lab with Jeyoon Bok, Ph.D. candidate at the Department of Mechanical Engineering.
Photo Credit: Marcin Szczepanski, Michigan Engineering

The first stem cell culture method that produces a full model of the early stages of the human central nervous system has been developed by a team of engineers and biologists at the University of Michigan, the Weizmann Institute of Science, and the University of Pennsylvania.

“Models like this will open doors for fundamental research to understand early development of the human central nervous system and how it could go wrong in different disorders,” said Jianping Fu, U-M professor of mechanical engineering and corresponding author of the study in Nature.

The system is an example of a 3D human organoid—stem cell cultures that reflect key structural and functional properties of human organ systems but are partial or otherwise imperfect copies.

“We try to understand not only the basic biology of human brain development, but also diseases—why we have brain-related diseases, their pathology, and how we can come up with effective strategies to treat them,” said Guo-Li Ming, who along with Hongjun Song, both Perelman Professors of Neuroscience at UPenn and co-authors of the study, developed protocols for growing and guiding the cells and characterized the structural and cellular characteristics of the model.

New study uncovers the importance of deepwater ecosystems for endangered species

Hawksbills typically forage on coral reefs where their diet is predominantly sponges.
Photo Credit: Jeanne A Mortimer

Using tracking data, a new study has revealed for the first time that hawksbill turtles feed at reef sites much deeper than previously thought.

Critically endangered hawksbill turtles are found in every ocean and are the most tropical of sea turtles. Adult hawksbills have long been considered to have a close association with shallow (less than 15 meters depth) seas where coral reefs thrive.

Young hawksbills drift in currents during their open water phase of their development before they move to seabed habitats. Hawksbills are usually seen foraging in coral reefs where their diet is predominantly sponges.

To study their feeding habits in more detail, researchers at Swansea, Florida and Deakin universities used high-accuracy GPS satellite tags to track 22 adult female hawksbills from their nesting site on Diego Garcia in the Chagos archipelago in the Indian Ocean to their foraging grounds.