Patent ID: 7200033
Filing Date: 2007-04-03
Classification: G11C,H01L

Abstract:
1. A method of writing to a random access memory (RAM) memory chip, comprising: providing a RAM memory chip comprising a plurality of magnetoresistive memory cells each including a magnetic tunnel junction having first and second magnetic regions made of magnetic material provided with magnetic anisotropy and being stacked in a parallel, overlying relationship separated by a layer of non-magnetic material, wherein the first magnetic region is provided with a fixed magnetic moment vector, while the second magnetic region comprises at least two ferromagnetic layers being antiferromagnetically coupled and being provided with a free magnetic moment vector which is switchable between the same and opposite directions with respect to the fixed magnetic moment vector of the first magnetic region, wherein the free magnetic moment vector is magnetically coupled to the magnetic fields of first and second current lines, and wherein the memory chip is surrounded by a coil for creating a magnetic offset field coupled to the free magnetic moment vector of the second magnetic region; turning-on a first current flowing through the coil to create a magnetic offset field in a preferred direction at a time to such that at least one switching field of the free magnetic moment vectors is reduced; turning-on a second current flowing through at least one of the first and second current lines at a time t turning-on a third current flowing through at least the other one of the first and second current lines at a time t turning-off the second current at a time t turning-off the first current to the coil.