Over the past 10 years, Miniature Storage techniques have taken center stage, thanks to the scientists who have been working in the field for years. These techniques are results of efforts to make computing technology as smaller as possible.
One of the biggest impediments to developing practical smaller computing devices is preserving information. For smaller computing devices, storage necessarily has to be atom size. Which further requires to build single-atom magnets.
“But a single magnetic atom is so sensitive, that its magnetic orientation remains stable only for a fraction of seconds.” which means it would not be able to retain the information for a longer time.
In a breakthrough study published in Science, EPFL (Ecole Polytechnique Fédérale de Lausanne) has built a single atom magnet that, although working at around 40 Kelvin (-233.15 degree Celsius), is the smallest and most stable to date.
Storing information in a single-atom magnet requires two specific orientations of each atomic magnetic moment represent a bit (0 or 1) of information. The dilemma here is to keep the single-atom magnet magnetized.
Or in other words, being able to hold the information in one of the bit states without an external magnetic field for a useful amount of time and at any practical temperature. This phenomenon is known as “magnetic remanence”. This is difficult to realize from single-atom magnet. Because of the diminished robustness against fluctuation from the environment which can unintentionally flip the magnetic state.
Previous studies on realizing remanence in a single atom proved premature and the question whether the required property of single-atom magnet can actually be achieved has remained an open question until now.
The team of EPFL led by Harald Brune and his colleagues at ETH Zurich, built a prototypical single-atom magnet based on atoms of the rare earth element holmium. The researchers, placed single holmium atoms on ultrathin films of magnesium oxide, which were previously grown on a surface of silver. The electron structure of single holmium atoms protects the magnetic field from being flipped.
Though the holmium atoms are stable at temperatures around 40 kelvin (-233.15 degree Celsius), but it is the closest we ever achieved to room temperature. Also, the previous demonstration was made up of 3-12 atoms. This makes EPFL study a worldwide record in terms of both size and stability.