Breakthrough could lead to data stored on single atoms

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Scientists have managed to store and read individual bits of data on atoms, which could pave the way for extremely small electronic devices or hard disks with massively more capacity than ones on the market today.

A group of researchers from the University of Nebraska and the Institut de Physique et de Chimie des Materiaux de Strasbourg in France wrote in a research paper that a phenomena, known as ballistic anisotropic magneto-resistance (BAMR), can allow electrons to have a positive or negative spin, representing either a zero or one. This advance could hereld vast improvements in data storage capacity.

The researchers said the work proved a new physical phenomenon existed and validated an earlier theory by another group working at the university.

"As a theorist, I am proud that our theoretical prediction of ballistic anisotropic magnetoresistance published earlier in Physical Review Letters was confirmed experimentally by our colleagues - researchers from UNL," said Evgeny Tsymbal, one of the researchers in the group. "We consider our achievement as the demonstration of a new quantum effect at the atomic scale."

Tsymbal proposed that BAMR would be evident when an atom-sized magnetised wire was placed in a second magnetic field. The wire atoms would magnetised in the direction of the field and this would allow data to be encoded onto the wire.

Using an electroplating technique putting a cobaly loop onto a silicon chip, the team measured conductance of magnetic metals by examining the electrons moving across tiny constrictions in wires, under the influence of a magnetic field. These atom-sized constrictions store the data.

Another researcher, Andrei Sokolov, said that if the constriction is small enough, electronics travel across the wire without scattering and the conductance becomes quantised and this changes step-wise with the constriction size. Basically the free flow of the electrons means that the electron spins align with the atoms and allow the data stored on the atoms to be read.

"If the wire is made of a ferromagnetic material, the electron transmission through the constriction varies in a quantized fashion when the magnetization changes its direction. This is what Evgeny has predicted theoretically and what we were able to observe experimentally," Sokolov said.

The researcher could only see what structures they had made when fabricating the constrictions in the wire with a scanning electron microscope. The structures that resulted from the plating process corresponded with what Tsymbal predicted.

The researchers said that with refinements to the electroplating process could potentially lead to a future generation of ultra-small electronic devices, such as ultra small magnetic read heads, quantum switches and logic circuits.

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