利用磁导率储存信息

Scientists have made promising steps in developing a new magnetic memory technology, which is far less susceptible to corruption by magnetic fields or thermal exposure than conventional memory. The findings, which report the use of magnetic permeability - how easily a magnetic field will magnetize a material - are published today, Friday 11th September, in the Journal of Physics D: Applied Physics.

These findings open up a new approach to a variety of applications from high-density radiation hard memory suitable for space travel to more secure ID cards.

In conventional magnetic memory, such as that in a computer, or the magnetic strip of a credit card, the memory is read by 'reading' the magnetization of the memory bit. As this magnetization is written using a magnetic field, it can also be erased by a magnetic field.

Magnetic permeability - an intrinsic property of 'soft' ferromagnets - is not changed by exposure to a magnetic field, and therefore information stored by programming changes in the magnetic permeability of each memory bit will not be erased by exposure to magnetic fields.

"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" explains Dr Alan Edelstein, an author on the paper. "I was surprised and pleased that we could make this approach work."

The technique used thermal heating with a laser to crystallize amorphous regions of ferromagnets. As the crystalline areas have a lower permeability than the amorphous areas, information can be read from the memory by reading the changes in a probe magnetic field.