A magnetic tunnel junction device usable as a memory cell or an external magnetic field sensor uses a multilayer of ferromagnetic layers in place of a single hard high-coercivity ferromagnetic layer in one of the two magnetic tunnel junction electrodes. The magnetic tunnel junction element in...http://www.google.com.au/patents/US5801984?utm_source=gb-gplus-sharePatent US5801984 - Magnetic tunnel junction device with ferromagnetic multilayer having fixed magnetic moment 
