A nano-scale materials do strange things. True is ferromagnetic metal compound in large quantities, but when its thickness is reduced to nanometric values, it becomes an insulator, and loses much of its ferromagnetism.
Still the same material, but holds a very different behavior.
Using a spectroscopic technique with atomic resolution, a team of researchers, who include David A. Muller, Lena Fitting Kourkoutis Cornell University, has concluded why this happens and how to grow extremely thin manganite films that retain their magnetic properties.
When this technique is sufficiently refined, it may be possible to lay the foundation for new developments that allow manganites and other oxides to replace silicon in electronic components based on thin films, in data storage and other technologies.
Previously, various research groups were grown thin layers of these classes and their results and suggested that there is a critical thickness of about 15 atomic layers, below which no conduction is possible.
Now, however, the authors of the new study shows that it is possible to reduce the thickness to a few atomic layers and keep driving.
The key is knowing how to grow perfect manganite layers without defects. The chemical composition has to be accurate, and even the smallest break in the lattice of atomic layers can spoil the conductivity of the films. These flaws do not matter much when working on a larger scale.
To examine the samples of the manganites created by his collaborators in Japan, Cornell University scientists used a special spectroscopic technique allows extreme precision with which to image the composition of the films of only a few atoms thick.
The manganites have good potential for the emerging field of spin based electronics, or spintronics, where the state of the spin of electrons is used to drive, handle and store the information. Conventional electronic circuits use only the state of charge of electrons (circulation or current), but these tiny particles also have a spin direction (“up” or “down”).
|Category: Nanotechnology||Tags: electrons, spectroscopic technique, thickness|