Ferromagnetic memory using soft magnetic material and hard magnetic

Abstract

A magnetic memory cell for storing binary encoded data and a memory constructed from these memory cells. A memory cell according to the present invention stores information in the direction of magnetization of a layer of magnetic material. The memory cell is constructed from a structure having a top electrode, a soft layer which includes a planar sheet of a soft magnetic material, a hard layer which includes a planar sheet of a hard magnetic material, and a bottom electrode, the soft and hard layers being sandwiched between the top and bottom electrodes. The hard and soft materials are chosen such that the magnitude to the magnetic field needed to magnetize the hard magnetic material is greater than the magnitude of the magnetic field needed to magnetize the soft magnetic material. The memory cell also includes a write circuit that generates first and second magnetic fields. The first and second magnetic fields are parallel to the planar sheet of the soft layer. The magnitudes of the first and second magnetic fields are less than that needed to magnetize the soft magnetic material. However, the magnitude of the vector sum of the first and second magnetic fields is greater than the magnetic field needed to magnetize the soft magnetic material but less than the magnetic field needed to magnetize the hard magnetic material.