Aurelia Butler

Ferromagnetism and antiferromagnetism have long been known to scientists as two classes of magnetic order of materials. Back in 2019, researchers at Johannes Gutenberg University Mainz (JGU) postulated a third class of magnetism, called altermagnetism. This altermagnetism has been the subject of heated debate among experts ever since, with some expressing doubts about its existence. Recently, a team of experimental researchers led by Professor Hans-Joachim Elmers at JGU was able to measure for the first time at DESY (Deutsches Elektronen-Synchrotron) an effect that is considered to be a signature of altermagnetism, thus providing evidence for the existence of this third type of magnetism. The research results were published in Science Advances.
Altermagnetism — a new magnetic phase
While ferromagnets, which we all know from refrigerator magnets, have all their magnetic moments aligned in the same direction, antiferromagnets have alternating magnetic moments. Thus, at the macroscopic level, the magnetic moments of antiferromagnets cancel each other out, so there is no external magnetic field — which would cause refrigerator magnets made of this material to simply fall off the refrigerator door. The magnetic moments in altermagnets differ in the way they are oriented. “Altermagnets combine the advantages of ferromagnets and antiferromagnets. Their neighboring magnetic moments are always antiparallel to each other, as in antiferromagnets, so there is no macroscopic magnetic effect, but, at the same time, they exhibit a spin-polarized current — just like ferromagnets,” explained Professor Hans-Joachim Elmers, head of the Magnetism group at JGU’s Institute of Physics.
Moving in the same direction with uniform spin
Electric currents usually generate magnetic fields. However, if one considers an altermagnet as a whole, integrating the spin polarization in the electronic bands in all directions, it becomes apparent that the magnetic field must be zero despite the spin-polarized current. If, on the other hand, attention is restricted to those electrons that move in a particular direction, the conclusion is that they must have a uniform spin. “This alignment phenomenon has nothing to do with spatial arrangements or where the electrons are located, but only with the direction of the electron velocity,” Elmers added. Since velocity (v) times mass (M) equals momentum (P), physicists use the term “momentum space” in this context. This effect was predicted in the past by theoretical groups at JGU led by Professor Jairo Sinova and Dr. Libor Šmejkal.
Proof obtained using momentum electron microscopy
“Our team was the first to experimentally verify the effect,” said Elmers. The researchers used a specially adapted momentum microscope. For their experiment, the team exposed a thin layer of ruthenium dioxide to X-rays. The resulting excitation of the electrons was sufficient for their emission from the ruthenium dioxide layer and their detection. Based on the velocity distribution, the researchers were able to determine the velocity of the electrons in the ruthenium dioxide. And using circularly polarized X-rays, they were even able to infer the spin directions.
For their momentum microscope, the researchers changed the focal plane that is normally used for observation in standard electron microscopes. Instead of a magnified image of the surface of the ruthenium oxide film, their detector showed a representation of momentum space. “Differing momentums appear at different positions on the detector. Put more simply, the different directions in which the electrons move in a layer are represented by corresponding dots on the detector,” said Elmers.
Altermagnetism may also be relevant to spintronics. This would involve using the magnetic moment of electrons instead of their charge in dynamic random access memory. As a result, storage capacity could be significantly increased. “Our results could be the solution to what is a major challenge in the field of spintronics,” suggested Elmers. “Exploiting the potential of altermagnets would make it easier to read stored information based on the spin polarization in the electronic bands.” More

The fields of chemistry and materials science are seeing a surge of interest in “self-driving labs,” which make use of artificial intelligence (AI) and automated systems to expedite research and discovery. Researchers are now proposing a suite of definitions and performance metrics that will allow researchers, non-experts, and future users to better understand both what these new technologies are doing and how each technology is performing in comparison to other self-driving labs.
Self-driving labs hold tremendous promise for accelerating the discovery of new molecules, materials and manufacturing processes, with applications ranging from electronic devices to pharmaceuticals. While the technologies are still fairly new, some have been shown to reduce the time needed to identify new materials from months or years to days.
“Self-driving labs are garnering a great deal of attention right now, but there are a lot of outstanding questions regarding these technologies,” says Milad Abolhasani, corresponding author of a paper on the new metrics and an associate professor of chemical and biomolecular engineering at North Carolina State University. “This technology is described as being ‘autonomous,’ but different research teams are defining ‘autonomous’ differently. By the same token, different research teams are reporting different elements of their work in different ways. This makes it difficult to compare these technologies to each other, and comparison is important if we want to be able to learn from each other and push the field forward.
“What does Self-Driving Lab A do really well? How could we use that to improve the performance of Self-Driving Lab B? We’re proposing a set of shared definitions and performance metrics, which we hope will be adopted by everyone working in this space. The end goal will be to allow all of us to learn from each other and advance these powerful research acceleration technologies.
“For example, we seem to be seeing some challenges in self-driving labs related to the performance, precision and robustness of some autonomous systems,” Abolhasani says. “This raises questions about how useful these technologies can be. If we have standardized metrics and reporting of results, we can identify these challenges and better understand how to address them.”
At the core of the new proposal is a clear definition of self-driving labs and seven proposed performance metrics, which researchers would include in any published work related to their self-driving labs. Degree of autonomy: how much guidance does a system need from users? Operational lifetime: how long can the system operate without intervention from users? Throughput: how long does it take the system to run a single experiment? Experimental precision: how reproducible are the system’s results? Material usage: what’s the total amount of materials used by a system for each experiment? Accessible parameter space: to what extent can the system account for all of the variables in each experiment? Optimization efficiency.”Optimization efficiency is one of the most important of these metrics, but it’s also one of the most complex — it doesn’t lend itself to a concise definition,” Abolhasani says. “Essentially, we want researchers to quantitatively analyze the performance of their self-driving lab and its experiment-selection algorithm by benchmarking it against a baseline — for example, random sampling.
“Ultimately, we think having a standardized approach to reporting on self-driving labs will help to ensure that this field is producing trustworthy, reproducible results that make the most of AI programs that capitalize on the large, high-quality data sets produced by self-driving labs,” Abolhasani says.
The work was done with support from the Dreyfus Program for Machine Learning in the Chemical Sciences and Engineering, under award number ML-21-064; the University of North Carolina Research Opportunities Initiative program; and the National Science Foundation, under grants 1940959 and 2208406. More

A new approach has allowed researchers at Aalto University to create a kind of metamaterial that has so far been beyond the reach of existing technologies. Unlike natural materials, metamaterials and metasurfaces can be tailored to have specific electromagnetic properties, which means scientists can create materials with features desirable for industrial applications.
The new metamaterial takes advantage of the nonreciprocal magnetoelectric (NME) effect. The NME effect implies a link between specific properties of the material (its magnetization and polarization) and the different field components of light or other electromagnetic waves. The NME effect is negligible in natural materials, but scientists have been trying to enhance it using metamaterials and metasurfaces because of the technological potential this would unlock.
“So far, the NME effect has not led to realistic industrial applications. Most of the proposed approaches would only work for microwaves and not visible light, and they also couldn’t be fabricated with available technology,” says Shadi Safaei Jazi, a doctoral researcher at Aalto. The team designed an optical NME metamaterial that can be created with existing technology, using conventional materials and nanofabrication techniques.
The new material opens up applications that would otherwise need a strong external magnetic field to work — for example, creating truly one-way glass. Glass that’s currently sold as ‘one-way’ is just semi-transparent, letting light through in both directions. When the brightness is different between the two sides (for example, inside and outside a window), it acts like one-way glass. But an NME-based one-way glass wouldn’t need a difference in brightness because light could only go through it in one direction.
“Just imagine having a window with that glass in your house, office, or car. Regardless of the brightness outside, people wouldn’t be able to see anything inside, while you would enjoy a perfect view from your window,” says Safaei. If technology succeeds, this one-way glass could also make solar cells more efficient by blocking the thermal emissions that existing cells radiate back toward the sun, which reduces the amount of energy they capture. More

Quantum bits can be described more precisely with the help of newly discovered harmonics as a team of 30 researchers reports in Nature Physics.
Physicists from Forschungszentrum Jülich and the Karlsruhe Institute of Technology have uncovered that Josephson tunnel junctions — the fundamental building blocks of superconducting quantum computers — are more complex than previously thought. Just like overtones in a musical instrument, harmonics are superimposed on the fundamental mode. As a consequence, corrections may lead to quantum bits that are 2 to 7 times more stable. The researchers support their findings with experimental evidence from multiple laboratories across the globe, including the University of Cologne, Ecole Normale Supérieure in Paris, and IBM Quantum in New York.
It all started in 2019, when Dennis Willsch and Dennis Rieger — two PhD students from FZJ and KIT at the time and joint first authors of the paper — were having a hard time understanding their experiments using the standard model for Josephson tunnel junctions. This model had won Brian Josephson the Nobel Prize in Physics in 1973. Excited to get to the bottom of this, the team led by Ioan Pop scrutinized further data from the Ecole Normale Supérieure in Paris and a 27-qubit device at IBM Quantum in New York, as well as data from previously published experiments. Independently, researchers from the University of Cologne were observing similar deviations of their data from the standard model.
“Fortunately, Gianluigi Catelani, who was involved in both projects and realized the overlap, brought the research teams together!,” recalls Dennis Willsch from FZ Jülich. “The timing was perfect,” adds Chris Dickel from the University of Cologne, “since, at that time, we were exploring quite different consequences of the same underlying problem.”
Josephson tunnel junctions consist of two superconductors with a thin insulating barrier in-between and, for decades, these circuit elements have been described with a simple sinusoidal model.
However, as the researchers demonstrate, this “standard model” fails to fully describe the Josephson junctions that are used to build quantum bits. Instead, an extended model including higher harmonics is required to describe the tunneling current between the two superconductors. The principle can also be found in the field of music. When the string of an instrument is struck, the fundamental frequency is overlaid by several harmonic overtones.
“It’s exciting that the measurements in the community have reached the level of accuracy at which we can resolve these small corrections to a model which has been considered sufficient for more than 15 years,” Dennis Rieger remarks.
When the four coordinating professors — Ioan Pop from KIT and Gianluigi Catelani, Kristel Michielsen and David DiVincenzo from FZJ — realized the impact of the findings, they brought together the large collaboration of experimentalists, theoreticians, and material scientists, to join their efforts in presenting a compelling case for the Josephson harmonics model. In the Nature Physics publication, the researchers explore the origin and consequences of Josephson harmonics. “As an immediate consequence, we believe that Josephson harmonics will help in engineering better and more reliable quantum bits by reducing errors up to an order of magnitude, which brings us one step closer towards the dream of a fully universal superconducting quantum computer,” the two first authors conclude. More

There is now a new addition to the magnetic family: thanks to experiments at the Swiss Light Source SLS, researchers have proved the existence of altermagnetism. The experimental discovery of this new branch of magnetism is reported in Nature and signifies new fundamental physics, with major implications for spintronics.
Magnetism is a lot more than just things that stick to the fridge. This understanding came with the discovery of antiferromagnets nearly a century ago. Since then, the family of magnetic materials has been divided into two fundamental phases: the ferromagnetic branch known for several millennia and the antiferromagnetic branch. The experimental proof of a third branch of magnetism, termed altermagnetism, was made at the Swiss Light Source SLS, by an international collaboration led by the Czech Academy of Sciences together with Paul Scherrer Institute PSI.
The fundamental magnetic phases are defined by the specific spontaneous arrangements of magnetic moments — or electron spins — and of atoms that carry the moments in crystals. Ferromagnets are the type of magnets that stick to the fridge: here spins point in the same direction, giving macroscopic magnetism. In antiferromagnetic materials, spins point in alternating directions, with the result that the materials possess no macroscopic net magnetisation — and thus don’t stick to the fridge. Although other types of magnetism, such as diamagnetism and paramagnetism have been categorised, these describe specific responses to externally applied magnetic fields rather than spontaneous magnetic orderings in materials.
Altermagnets have a special combination of the arrangement of spins and crystal symmetries. The spins alternate, as in antiferromagnets, resulting in no net magnetisation. Yet, rather than simply cancelling out, the symmetries give an electronic band structure with strong spin polarization that flips in direction as you pass through the material’s energy bands — hence the name altermagnets. This results in highly useful properties more resemblant of ferromagnets, as well as some completely new properties.
A new and useful sibling
This third magnetic sibling offers distinct advantages for the developing field of next-generation magnetic memory technology, known as spintronics. Whereas electronics makes use only of the charge of the electrons, spintronics also exploits the spin-state of electrons to carry information.
Although spintronics has for some years promised to revolutionise IT, it’s still in its infancy. Typically, ferromagnets have been used for such devices, as they offer certain highly desirable strong spin-dependent physical phenomena. Yet the macroscopic net magnetisation that is useful in so many other applications poses practical limitations on the scalability of these devices as it causes crosstalk between bits — the information carrying elements in data storage.

More recently, antiferromagnets have been investigated for spintronics, as they benefit from having no net magnetisation and thus offer ultra-scalability and energy efficiency. However, the strong spin-dependent effects that are so useful in ferromagnets are lacking, again hindering their practical applicability.
Here enter altermagnets with the best of both: zero net magnetisation together with the coveted strong spin-dependent phenomena typically found in ferromagnets — merits that were regarded as principally incompatible.
“That’s the magic about altermagnets,” says Tomáš Jungwirth from the Institute of Physics of the Czech Academy of Sciences, principal investigator of the study. “Something that people believed was impossible until recent theoretical predictions is in fact possible.”
The search is on
Murmurings that a new type of magnetism was lurking began not long ago: In 2019, Jungwirth together with theoretical colleagues at the Czech Academy of Sciences and University of Mainz identified a class of magnetic materials with a spin structure that did not fit within the classic descriptions of ferromagnetism or antiferromagnetism.
In 2022, the theorists published their predictions of the existence of altermagnetism. They uncovered more than two hundred altermagnetic candidates in materials ranging from insulators and semiconductors, to metals and superconductors. Many of these materials have been well known and extensively explored in the past, without noticing their altermagnetic nature. Due to the huge research and application opportunities that altermagnetism poses, these predictions caused great excitement within the community. The search was on.

X-rays provide the proof
Obtaining direct experimental proof of altermagnetism’s existence required demonstrating the unique spin symmetry characteristics predicted in altermagnets. The proof came using spin- and angle resolved photoemission spectroscopy at the SIS (COPHEE endstation) and ADRESS beamlines of the SLS. This technique enabled the team to visualise a tell-tale feature in the electronic structure of a suspected altermagnet: the splitting of electronic bands corresponding to different spin states, known as the lifting of Kramers spin degeneracy.
The discovery was made in crystals of manganese telluride, a well-known simple two-element material. Traditionally, the material has been regarded as a classic antiferromagnet because the magnetic moments on neighbouring manganese atoms point in opposite directions, generating a vanishing net magnetisation.
However, antiferromagnets should not exhibit lifted Kramers spin degeneracy by the magnetic order, whereas ferromagnets or altermagnets should. When the scientists saw the lifting of Kramers spin degeneracy, accompanied by the vanishing net magnetisation, they knew they were looking at an altermagnet.
“Thanks to the high precision and sensitivity of our measurements, we could detect the characteristic alternating splitting of the energy levels corresponding to opposite spin states and thus demonstrate that manganese telluride is neither a conventional antiferromagnet nor a conventional ferromagnet but belongs to the new altermagnetic branch of magnetic materials,” says Juraj Krempasky, beamline scientist in the Beamline Optics Group at PSI and first author of the study.
The beamlines that enabled this discovery are now disassembled, awaiting the SLS 2.0 upgrade. After twenty years of successful science, the COPHEE endstation will be completely integrated into the new ‘QUEST’ beamline. “It was with the last photons of light at COPHEE that we made these experiments. That they gave such an important scientific breakthrough is very emotional for us,” adds Krempasky.
“Now that we have brought it to light, many people around the world will be able to work on it.”
The researchers believe that this new fundamental discovery in magnetism will enrich our understanding of condensed-matter physics, with impact across diverse areas of research and technology. As well as its advantages to the developing field of spintronics, it also offers a promising platform for exploring unconventional superconductivity, through new insights into superconducting states that can arise in different magnetic materials.
“Altermagnetism is actually not something hugely complicated. It is something entirely fundamental that was in front of our eyes for decades without noticing it,” says Jungwirth. “And it is not something that exists only in a few obscure materials. It exists in many crystals that people simply had in their drawers. In that sense, now that we have brought it to light, many people around the world will be able to work on it, giving the potential for a broad impact.” More

In the realm of quantum mechanics, the ability to observe and control quantum phenomena at room temperature has long been elusive, especially on a large or “macroscopic” scale. Traditionally, such observations have been confined to environments near absolute zero, where quantum effects are easier to detect. But the requirement for extreme cold has been a major hurdle, limiting practical applications of quantum technologies.
Now, a study led by Tobias J. Kippenberg and Nils Johan Engelsen at EPFL, redefines the boundaries of what’s possible. The pioneering work blends quantum physics and mechanical engineering to achieve control of quantum phenomena at room temperature.
“Reaching the regime of room temperature quantum optomechanics has been an open challenge since decades,” says Kippenberg. “Our work realizes effectively the Heisenberg microscope — long thought to be only a theoretical toy model.”
In their experimental setup, published in Nature, the researchers created an ultra-low noise optomechanical system — a setup where light and mechanical motion interconnect, allowing them to study and manipulate how light influences moving objects with high precision.
The main problem with room temperature is thermal noise, which perturbs delicate quantum dynamics. To minimize that, the scientists used cavity mirrors, which are specialized mirrors that bounce light back and forth inside a confined space (the cavity), effectively “trapping” it and enhancing its interaction with the mechanical elements in the system. To reduce the thermal noise, the mirrors are patterned with crystal-like periodic (“phononic crystal”) structures.
Another crucial component was a 4mm drum-like device called a mechanical oscillator, which interacts with light inside the cavity. Its relatively large size and design are key to isolating it from environmental noise, making it possible to detect subtle quantum phenomena at room temperature. “The drum we use in this experiment is the culmination of many years of effort to create mechanical oscillators that are well-isolated from the environment,” says Engelsen.
“The techniques we used to deal with notorious and complex noise sources are of high relevance and impact to the broader community of precision sensing and measurement,” says Guanhao Huang, one of the two PhD students leading the project.

The setup allowed the researchers to achieve “optical squeezing,” a quantum phenomenon where certain properties of light, like its intensity or phase, are manipulated to reduce the fluctuations in one variable at the expense of increasing fluctuations in the other, as dictated by Heisenberg’s principle.
By demonstrating optical squeezing at room temperature in their system, the researchers showed that they could effectively control and observe quantum phenomena in a macroscopic system without the need for extremely low temperatures. Top of Form
The team believes the ability to operate the system at room temperature will expand access to quantum optomechanical systems, which are established testbeds for quantum measurement and quantum mechanics at macroscopic scales.
“The system we developed might facilitate new hybrid quantum systems where the mechanical drum strongly interacts with different objects, such as trapped clouds of atoms,” adds Alberto Beccari, the other PhD student leading the study. “These systems are useful for quantum information, and help us understand how to create large, complex quantum states.” More

In supramolecular chemistry, the self-assembly state of molecules plays a significant role in determining their tangible properties. Controlling the self-assembled state has garnered significant attention as it can be exploited to design materials with desired properties like charge transport capability and fluorescence wavelength. For years, scientists have been trying to decipher how molecular organization impacts the properties of supramolecular assemblies that are in the nano (10 nm) and mesoscopic (10-1000 nm) scales. However, the study of structures with supramolecular polymer assemblies derived from the same monomer is often hindered by dynamic structural changes and immature control over self-assemblies.
A recent study published on January 1, 2024, in the Journal of the American Chemical Society, investigated the properties of one-dimensional mesoscale supramolecular assemblies of two different structures composed of the same luminescent molecule. It showed how two structures showed very different properties depending on whether they had their molecules arranged in a closed circular pattern or not. The study was led by Prof. Shiki Yagai from Chiba University, with Sho Takahashi, a doctoral course student at the Graduate School of Science and Engineering at Chiba University, as the first author. It also included Prof. Martin Vacha from the Department of Materials Science and Engineering at Tokyo Institute of Technology, and Dr. Hikaru Sotome from the Graduate School of Engineering Science at Osaka University as corresponding authors.
“The geometrical beauty of a circular structure, which has no termini and no corners, has fascinated people. Chemists have realized the synthesis of giant cyclic molecules using various approaches not only to create beautiful structures but also to compete in the elegance of the process of synthesizing such beautiful structures,” says Prof. Yagai, speaking of the inspiration behind this study. “The best example of nature utilizing the functional beauty of circular structures would be the light-harvesting antenna organ (LH2, LH1) of purple photosynthetic bacteria. LH2 has a beautiful circular structure due to the protein’s outstanding self-organizing ability, and it is thought that by arranging chlorophyll dyes in a circular array based on this framework, lean light collection and excitation energy transfer are achieved.”
Through the self-assembly of luminescent molecules synthesized based on their own molecular design, the team obtained a mixture of two one-dimensional π?conjugated molecular aggregates with different structures, namely terminus-free cyclic structures (toroids) and randomly coiled structures. The mixture exhibited low-energy and low-intensity luminescence.
The two structures were separated using a novel dialysis technique that exploited the difference in their kinetic stability. Post-separation, it was shown that the terminus-free closed toroidal structure led to higher energy and more efficient luminescence when compared to random coils. The team carried out ultrafast laser spectroscopy to investigate the mechanism of their topology-dependent fluorescence properties. The results indicated random coils with termini lost excitation energy due to defects generated by fluctuations in solution, unlike toroids that were not easily deformed and exhibited fluorescence without energy loss. Furthermore, it was found that in the mixed solution of toroids and random coils, the excitation energy was transferred from the toroid to the random coil due to the agglomeration of both assemblies, and only the random coil-derived luminescence was observed.
This study establishes morphological control of materials at the mesoscale as a possible new guideline for the design of functional materials. It also highlights that in the case of materials that are prone to supramolecular polymorphism, such as the toroid and random coil, it is essential to purify the assemblies before analyzing their photophysical properties. If not separated, the results obtained might only reflect biased properties instead of distinct ones due to energy transfer between different structures.
The researchers are hopeful that these insights can encourage the development of high-performance flexible devices using cyclic molecular assemblies. “We can gladly say that a correlation between structural beauty and functional beauty has been found here, even in meso-scale molecular assemblies. We believe that the insights from our study could help improve the performance of solar cell devices and light-emitting devices in the long run, thereby facilitating their widespread acceptability and enriching people’s lives along the way,” concludes Prof. Yagai. More

Chiral skyrmions are a special type of spin textures in magnetic materials with asymmetric exchange interactions. They can be treated as quasi-particles and carry integer topological charges. Scientists from Waseda University have recently studied the random walk-behaviors of chiral skyrmions by simulating their dynamics within a ferromagnetic layer surrounded by chiral flower-like obstacles. The simulations reveal that the system behaves like a topological sorting device, indicating its use in information processing and computing devices.
In nature, the collective motion of some birds and fish, such as flocks of starlings and shoals of sardines, respectively, can generate impressive dynamic phenomena. Their study constitutes active matter science, which has been a topic of great interest for the past three decades. The unique collective dynamics of active matter are governed by the motion of each individual entity, the interactions among them, as well as their interaction with the environment. Recent studies show that some self-propelling molecules and bacteria show circular motion with a fixed chirality (the property of an object where it cannot be superimposed upon its mirror image through any number of rotations or translations), which can enable the selection of molecules and bacteria with specific chirality based on their dynamics. However, there is a lack of research on active matter-like objects in non-biological magnetic and ferroelectric materials for electronic device applications.
In this regard, chiral skyrmions are promising. They are a special type of spin textures in magnetic materials with asymmetric exchange interactions, which can be treated as quasi-particles. They carry integer topological charges and have a fixed chirality of either +1 or -1.
Recently, a group of scientists, led by Professor Masahito Mochizuki from the Department of Applied Physics at Waseda University and including Dr. Xichao Zhang from Waseda University and Professor Xiaoxi Liu from Shinshu University, has extensively studied the active matter behaviors of chiral skyrmions. Their paper was made available online on December 6, 2023, and published in Volume 23, Issue 24 of the journal Nano Letters on December 27, 2023.
In this study, the scientists placed chiral skyrmions within chiral nanostructure obstacles in the shape of a simple chiral flower. They then studied the random-walk dynamics of the thermally activated skyrmion interacting with the chiral flower-like obstacle in a ferromagnetic layer, which could create topology-dependent outcomes. “Our research demonstrates for the first time that magnetic chiral skyrmions exhibit active matter-like behaviors even though they are of non-biological origin and even merely intangible spatial patterns,” says Prof. Mochizuki, highlighting the novelty of their study.
The skyrmion with chirality -1 has the potential to leave a left chiral flower, and the skyrmion with a chirality of +1 has the potential to leave a right chiral flower. The researchers conducted a series of simulations to observe how skyrmions would behave in both cases at different temperatures: 100 K, 150 K, 180 K, and 200 K. They set the simulation time as 500 ns, with a time step of 0.5 ns. The team found that depending on the combination of variables, the skyrmion either remains within the obstacle or escapes it. Since the motion of the skyrmion is due to temperature-dependent Brownian motion, which is disorderly in nature, this is an interesting case of getting an orderly result through disordered motion. Notably, this system can be used to develop a topological sorting device.
When asked about the long-term implications of their work, Prof. Liu remarks: “Our research results may be useful for building future information processing and computing devices with high storage density and low power consumption.”
“In the long term, they may provide guidelines for the design and development of non-conventional electronic and spintronic hardware, where the information is carried by topological spin textures in nanostructures. This achievement is expected to improve people’s lives as they would be able to process information in an energy-efficient manner, leading to a greener society,” concludes Dr. Zhang. More