New magnetic memory that is far less susceptible to corruption than traditional technology could lead to more secure bank cards, say scientists.
Conventional magnetic memory used in computers for the black strip on the back of a credit card works by 'reading' information about the magnetisation of memory bits, but because this magnetisation is written using a magnetic field it can also be erased by one.
However, by using changes in the magnetic permeability of soft ferromagnets to store information instead, the new memory technology is immune to magnetic corruption, as permeability is not changed by exposure to a magnetic field. Magnetic permeability is a measure of how easily a magnetic field will magnetize a material.
Concerns about the stability of magnetic strips in credit cards have seen providers turn to RF chips, but there are growing concerns about the ability of a passer-by to snoop on them using an RF reader.
The close proximity required for the probe magnetic field to read the memory suggests the new technology could provide a stable and secure alternative to the two older solutions.
“It was a big step just coming up with the idea of using magnetic permeability to store information and coming up with a practical way of getting the memory near the sensor so that it can be read," said Dr Alan Edelstein, an author on the paper. “I was surprised and pleased that we could make this approach work.”
A paper published in The Journal of Physics D: Applied Physics today describes how the researchers used thermal heating with a laser to crystallise amorphous regions of the ferromagnets.
These crystalline areas have a lower permeability than the amorphous areas, meaning information can be read from the memory by reading the changes in a probe magnetic field.
The researchers also found that the memory is less prone to degradation from exposure to gamma radiation – an important factor for memory used for space travel, as the memory would need less shielding, making it lighter.
The researchers are now working on a technique to make the memory re-writable. “We’ve demonstrated the ability to rewrite bits for a read/write memory and hope to publish the results soon,” added Edelstein.