Magnetic RAM should ultimately do better. Both kinds of chips require high power and wear out after less than a million write operations. Magnetic memories will also compete with ferroelectric devices, in which a 0 or 1 is recorded by changing the position of atoms in a crystal. Ramtron in Colorado Springs recently produced 64-kilobit versions that the firm claims are nearly as fast as DRAM and last for years. But it has apparently failed to convince many customers, because sales fell in 1998 and the company continues to lose money.
Electrons tunnel more freely if the two fields are aligned.
Two current pulses in a write operation can flip the field in the upper layer, changing its data. The cell's state is read by two current pulses, positive and then negative. In the write operation, strong current in both conductors will change both magnetic fields. The magnetic RAM teams have divided along scientific lines to pursue three distinct approaches. Minn. Unfortunately, GMR devices consume so much current that their transistors burn out if shrunk to the submicron sizes that market economics demand.