Almost all information that is stored on hard disc drives or cloud servers is recorded in magnetic media. Magnetic media is non-volatile and cheap. Portable devices like cell phones and tablets use other forms of non-magnetic memory because the technology is based on magnetism. This is impractical and not energy efficient. Mass data storage and portable devices collect and process information is the name of the game today, so developers are searching to find a smaller, faster, cheaper and more energy efficient ways of processing and storing more and more data.
Physicists at the University of Nottingham have ventured into researching the use of magnetic domain walls (local regions of magnetic charge that is usually driven by magnetic fields) to increase the capacity for information storage and logical processing. Through their research, the team has discovered a phenomenon that has allowed them to manipulate the structure of the magnetic domain wall.
The research was carried out by researchers in the Spintronic Group in the School of Physics and Astronomy in collaboration with York University. It could prove a route to creating a new class of highly efficient, non-volatile information processing and storage technology.
The main benefit of magnetism is that the magnetic state remains stable when power is removed from the device, which enables non-volatile storage information. Most processors use random access memory (RAM) chips to store information using electrical charge. Electrical charges are fast, but the charge dissipates when the device is turned off.
Magnetic random access memory (MRAM) is new, promising a form of non-volatile Ram that is based on magnetism that has found applications in some niche markets. In MRAM information is written with an electrical current that generates heat and stray magnetic fields. There are currently no technologies that use magnetism to process information.
A solution to these problems might lie in the use of magnetic domain walls. A magnetic domain wall forms in a magnetic wire and separates regions where magnetization points in opposite direction. Under some conditions, it consists of a region in which the magnetization rotates around a central vortex core, which points into or out of a wire.
Previously it has been proven that chirality can be manipulated by applying magnetic fields to complicated nano wire geometries. But magnetic fields waste energy and limit the ability to address individual domain walls selectively.
Researchers have discovered a way to control the chirality of the vortex domain wall through using an electric field.
Dr. Andrew Rushforth, from the School of Physics and Astronomy, said, "We didn't set out to switch the chirality of the domain walls. We were actually trying to see if we could make them move. When we noticed that the chirality was switching, we were rather surprised, but we realized that it was an interesting and novel effect that could potentially have important applications. We then had to go back to the office and perform micro magnetic calculations to understand why and how the phenomenon occurs."
The research team used the strain that was induced by an electric field applied to piezoelectric material that deforms mechanically in response to an electric field, in order to manipulate the chirality of the domain wall.
This is at the early stage. Until now it hasn’t been obvious to how someone could control magnetic domain walls reversibly and predictably by using electric fields. The research helps solve the issue, but there are still other practical issues that need to be fixed.
The next stage of this researcher will be to investigate how the chirality switch depends on the material properties, geometry and dimensions of the magnetic wire.
A paper on this research was published in here.