US Patent 7200033 MRAM with coil for creating offset field

An MRAM memory chip includes a plurality of magnetoresistive memory cells each including a magnetic tunnel junction having first (fixed) and second (free) magnetic regions, where the second magnetic region includes at least two ferromagnetic layers that are antiferromagnetically coupled, wherein a coil surrounds the memory chip for creating a magnetic offset field. Further, a method of writing to an MRAM chip includes bringing the memory cells into an active state exhibiting a reduced switching field before writing thereto and bringing the memory cells into a passive state exhibiting enlarged switching field after writing thereto.