Magnetic bubbles appear in quantum dots

Scientists have observed " mathematical " objects, called " magnetic balls " in nano dots with strong perpendicular anisotropies. They also observed that the triploid state contains concentric circles with different degrees in the same material. Along with interesting properties for basic research, this word structure can be a very useful solution for information storage applications.

"In nanoscale magnetic particles we study (FePt nanoparticles), magnetic dipoles of atoms are organized in configurations, or magnetic distribution, and one of them may have Interesting properties, " - Christoforos Moutafis (University of Cambridge, UK), a member of the research team told Nanotechweb.org. " The axial symmetry state that we have identified is the expression of unusual mathematical objects ."

The team, including researchers from Japan and Germany, observed magnetic structures using magnetic force microscopes, by photographing arrays of nanotips with different diameters. These dots are made from thin films of FePt (fabricated by cathode sputtering), then create dot matrices using electron beam lithography. In the small dots, they recorded the bubbles from the simple circle imprisoned at the center of the dot."These are cylindrical magnetic domes that have parallel magnetic degrees and perpendicular to the nanoscale plane," explains Moutafis. "We call them the" bi-domain "state, or" monobubble "state."

Figure 1. Magnetic bubbles observed by magnetic force microscopes
( Phys. Rev. B 76 (2007) 104426 ).

In larger dots, more complex random pattern patterns were observed with " monobubbles " appearing only in certain diameter and thickness dots . According to the researchers, these magnetic bubbles are the same as magnetic vortices that often appear in magnetic particles with weak magnetic anisotropy with outer wall swirling around the circle. The state of "Tri-domain" (Tri-domain) or " three rings ", including concentric circles with different degrees of observation. These structures are also said to have higher orderly foam states.

"Magnetic nano dots are" laboratories "to study the hierarchy of precise mathematical objects" - Moutafis said. " FePt alloys have unusual strong magnetic properties, such as giant magnetic anisotropies, making it one of the best candidates for future technology applications such as data storage." .

Figure 2. Phase diagram of the potential for bubbles to correspond to the nano dot radius and dot thickness (Phys. Rev. B 76 (2007) 104426).

Moutafis also goes on to say that the magnetic states observed react in a particular way when there are external influences such as the effect of magnetic fields or currents."This makes sense for both basic research and applicability. Our research has shown a way to explore the dynamics of magnetic nanoscale configurations."

More detailed insights into how these states and their evolution can allow scientists to manipulate them. For example, individual nano dots can be used to encode some bits of information simply by changing the word state. " This can help find applications, such as in labels used for biological areas, or in general components where information encryption is needed " - explained. of Moutafis.

Researchers have begun to conduct modeling calculations and simulate these phenomena and plan to conduct more detailed experiments on photography. " We are fascinated by finding brief phenomena at short intervals, which seem to be placed between different magnetic configurations and controlling their kinetic processes (according to preliminary results). set) " - Moutafis said. "Only in particular about the scientific properties, the ultra-fast island potential is very important for technology because the average time is very short, a prerequisite for future modern components".

Christoforos Moutafis is a graduate student at Cambridge University (UK) and this work has just been published in Physical Review B.

Christoforos Moutafis is a PhD student of Cambridge University, a member of the research team (Photo: VatlyVietNam)

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According to Physical Review B & Nanotechweb.org, Vietnamese Physics