Skip to main content

First observation of a square lattice of merons and antimerons

First observation of a square lattice of merons and antimerons :


Scientists have, for the first time, observed a square lattice of merons and antimerons -- tiny magnetic vortices and antivortices that form in a thin plate of the helical magnet Co8Zn9Mn3. By finely varying a magnetic field applied perpendicularly to the thin plate, the researchers were able to induce a transformation between the square lattice of merons-antimerons and a hexagonal lattice of skyrmions, another form of vortex that is topologically different from merons and antimerons.
The ability to manipulate nanometer-scale spin textures such as merons and skyrmions is a key to the development of spintronics -- next-generation electronic devices that are very low in power consumption. The secret to their low power consumption is that they make use of the topological spin texture -- a property that emerges when electrons interact in a solid.
To perform the experiments, published in Nature, the group used a thin magnetic sample made of an alloy of cobalt, zinc, and manganese, Co8Zn9Mn3, which is known as a chiral magnet. They used an extremely weak magnetic field to coax the tiny vortices to form in the thin sample, and observed them with Lorentz electron microscopy. "It is well known in nature," says Xiuzhen Yu of the RIKEN Center for Emergent Matter Science (CEMS), the first author of the paper, "that external stimuli can trigger a structural transition of crystals between tetragonal and hexagonal lattices, and it had been predicted that this would be seen in topological spin-textures as well. It was very satisfying to be able to show that this idea was indeed true, when we witnessed the merons transformed into skyrmions as we carefully increased the magnetic field."
The experiments did, however, give the researchers some surprises. Using the thin plate sample, they experimented with lowering the temperature to see how it would affect the textures. According to Yu, "We found that the skyrmions were very robust, lasting even as we lowered the temperature of the thin plate, but the merons and antimerons were much more sensitive, and relaxed into spin helices as the temperature fell. This could have implications for the manipulation of these textures in future spintronic devices. In the future, we plan to do studies using not only magnetic anisotropy, but also local strain to control spin textures."

Comments

Post a Comment

Popular posts from this blog

Size matters: New data reveals cell size sparks genome awakening in embryos

Transitions are a hallmark of life. When dormant plants flower in the spring or when a young adult strikes out on their own, there is a shift in control. Similarly, there is a transition during early development when an embryo undergoes biochemical changes, switching from being controlled by maternal molecules to being governed by its own genome. For the first time, a team from the Perelman School of Medicine at the University of Pennsylvania found in an embryo that activation of its genome does not happen all at once, instead it follows a specific pattern controlled primarily by the various sizes of its cells. The researchers published their results this week as the cover story in  Developmental Cell . In an early embryo undergoing cell division, maternally loaded RNA and proteins regulate the cell cycle. The genomes of the zygote -- a term for the fertilized egg -- are initially in sleep mode. However, at a point in the early life of the embryo, these zygotic nuclei "wake...
Post a Comment
Read more

Home births as safe as hospital births: International study suggests

A large international study led by McMaster University shows that low risk pregnant women who intend to give birth at home have no increased chance of the baby's perinatal or neonatal death compared to other low risk women who intend to give birth in a hospital. The results have been published by  The Lancet 's  EClinicalMedicine  journal. "More women in well-resourced countries are choosing birth at home, but concerns have persisted about their safety," said Eileen Hutton, professor emeritus of obstetrics and gynecology at McMaster, founding director of the McMaster Midwifery Research Centre and first author of the paper. "This research clearly demonstrates the risk is no different when the birth is intended to be at home or in hospital." The study examined the safety of place of birth by reporting on the risk of death at the time of birth or within the first four weeks, and found no clinically important or statistically different risk between home...
Post a Comment
Read more

Molecular adlayer produced by dissolving water-insoluble nanographene in water

Molecular adlayer produced by dissolving water-insoluble nanographene in water : "Nanographene incorporated micelle capsules" can be prepared by simply pulverizing and mixing nanographene with amphiphilic V-shaped anthracene molecules in water at room temperature. Even though nanographene is insoluble in water and organic solvents, Kumamoto University (KU) and Tokyo Institute of Technology (Tokyo Tech) researchers have found a way to dissolve it in water. Using "molecular containers" that encapsulate water-insoluble molecules, the researchers developed a formation procedure for a nanographene adlayer, a layer that chemically interacts with the underlying substance, by just mixing the molecular containers and nanographene together in water. The method is expected to be useful for the fabrication and analysis of next-generation functional nanomaterials. Graphene is a single layer of carbon atoms arranged in sheet form. It is lighter than metal wit...
Post a Comment
Read more