According to foreign media reports, physicists who are looking for a rare magnetic spin structure have discovered another object with its own characteristics hidden in the ultra-thin magnetic film structure, which they call disproportionate spin crystals. A research team from the University of Warwick in the United Kingdom reported this discovery in Nature Communications, which may provide new possibilities for computer memory and storage technologies.
Researchers initially planned to look for Skyrmion, which is a rotating magnetic spin structure that theoretically exists in the specific magnetic material . Because of its unique characteristics and the potential of a new generation of energy-efficient data storage, physicists are very interested in this. In order to find them, scientists look for the abnormal behavior of Hall effect , which causes electrons to exhibit different behaviors when passing through conductive materials and use resistivity to measure them.
In order to induce this effect, the research team combined a ferroelectric material, an extremely thin film of lead titanate with another ferromagnet, and a strontium salt film to make samples. These layers are flat at the atomic level, only 5 to 6 units (3 nanometers) thick.
The electric field generated by the ferroelectric layer distorts the atomic structure of the ferromagnet and breaks its symmetry. The researchers measured this symmetry destruction by using an atomic precision electron microscope, and at the same time, they were able to measure the material's resistivity separately and confirmed the existence of features similar to the topological Hall effect, which is what Skymion expected.
Then the researchers used a magnetic force microscope to examine the topological structure of the material's atomic structure, which formed a rectangular-based lattice instead of the hexagon as they expected. In this lattice is the magnetic domain, in the magnetic domain, Skyrmion will be found as independent, isolated particles. Instead, these areas are more like beads on a string or necklace, and these beads will never form a complete circle.
The lead author of the study, Sam Seddon, said: "Once you double check these images,You will realize that, in fact, this is not like a Skyrmion at all.
"A Skymion will produce its own complex Hall effect. When similar effects are observed, it is usually considered Skymion's signature. We found a very ordered domain structure, just like the formation of Skymion lattices, but they are only chiral and have no topological protection. Evidence from real-space imaging shows that you do not need a topological domain to produce this Hall effect.
Ferroelectric materials and ferromagnetic materials are important components of computer storage and storage technologies. For example, due to robustness and the ability to work at extreme temperatures, materials very similar to lead titanate are often used Computer memory for automotive electronic systems.
Professor Marin Alexe, the co-author of the paper from the University of Warwick, stated that “people are very interested in the interface between ferroelectric materials and ferromagnetic materials , such as for new computer memory. Since the polarization of the ferroelectric can be permanently switched, this changes the quantum effect in the ferromagnet, which may give us the material direction of the next quantum computer. This will require stable materials that work at extreme temperatures. They have low power consumption and can store information for a long time, so all the ingredients are here. topology is the transformation of certain mathematical concepts in real life, and is now the core of new discoveries in physics. At the University of Warwick, we have an extraordinary and advanced infrastructure that allows us to solve problems theoretically, observe atomic structures, and study functional properties under extreme temperatures and fields, especially magnetic fields. We can provide a basis for engineers to develop new technologies. ”
.-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-