Researchers at MIT have developed a new way to control the movement of the magnetic domains – the most important technology in magnetic memory system, such as a computer's hard drive. The new method requires little energy to write and no power to maintain the stored information, and could lead to a new generation of extremely power-efficient data storage.
The new method controlling magnetism by applying a voltage, rather than a magnetic field. It can lead to magnetic storage devices where data is written on microscopic Nanowires with magnetic tracks, or "bits" of data speeds along them like cars on a racetrack.
The new results are described in a paper published this week in the journal Nature Nanotechnology, written by Assistant professor of materials science and engineering and PhD Geoffrey Beach Uwe Bauer and Satoru Emori.
"Several hundred years, if you had the magnetic material and you wanted to change the direction in which the material was magnetized, you needed another magnet," Beach says. His team's work represents a whole new way to change the magnetic States with just a change in voltage, with no magnetic field — a much lower power process. What's more, when the magnetic State is switched, it holds the change, which allows stable data storage requiring no power except during reading and writing.
The researchers showed that this effect can be used to new concepts such as "racetrack memory," with magnetic pieces speeding along a magnetic track. There have been laboratory demonstrations of such devices, no one has come close to profitability for data storage: the missing piece has been a way to precisely control position and electric pick individual magnetic bits racing along the magnetic track.
"Magnetic fields are very difficult to locate," Beach says: If you try to create small magnetic pieces on a Nanowire or track, the magnetic fields from the electromagnets are used to read and write data tend to spread out, making it difficult to prevent interaction with adjoining Strip, especially as devices become smaller and smaller.
But the new system can precisely select individual magnetic bits represented by small domains in a Nanowire. MIT device can stop the movement of the magnetic domains, speed of 20 meters per second, or about 45 km/h, "on a dime," Beach said. They can then be released on demand simply by alternating voltage.
To achieve this feat, built the MIT team a new type of device that controls the magnetism in much the same way that a transistor controls the flow of electricity; the main ingredient is one layer of ion-rich materials in which the atoms are stripped of electrons, leaving them with an electrical charge. A voltage applied to a small electrode over this thin layers can attract or repel the ions; the ions, in turn can change the properties of an underlying magnetic and stop the flow of magnetic domains. This can lead to a new family of "magneto-Ionic" devices, the researchers suggest.
The effect depends on the chemical interactions at the boundary between the thin layers of magnetic metal and solid-state electrolyte materials sandwiched together, says strand. "So it really is chemistry that determines the Interfacial tension of the magnetic properties," he said.
In practice such a system would use a wire or strip of ferromagnetic material with a series of regularly spaced, tiny electrodes on top of it. The magnetic bits between these electrodes can then selectively be written or read.
When the orientation of the magnetic little between two electrodes has been set up by this device, says "the intrinsic will retain its direction and position even in the absence of power," Beach. So, in practice, you could put a little magnetic, "then turn off the power before you need to read it back," he says.
"Because the magnetic switching requires no magnetic field, there is next to no energy dissipation, says shore. What is more, the resulting pinning of magnetic bits are extremely strong, resulting in a robust storage system.
The main ingredients in the system is "very simple oxide materials," says Bauer. Particularly used these tests gadolinium oxide, already used to make capacitors and semiconductor manufacturing.
Dan Allwood, researchers in materials science at the University of Sheffield who did not take part in this research, saying it "not only offers a novel technical course to control dynamic excitation processes in patterned nanostructures, but doing so also presents new physical processes in how stress can affect the magnetic behavior more generally. Understand the detailed origins of these effects may allow the creation of simple, low-power computing devices. "
In addition to magnetic systems, the MIT team says, this technology can also be used to create new electronic devices based on spintronics, in which information is carried out by the spin orientation of the atoms. "It opens up a whole new domain," says Beach. "You can do both data storage and calculation, potentially at much lower power."