| 主权项 |
1. Method for writing a plurality of data bits to a magnetic random access memory (MRAM) cell comprising:
a magnetic tunnel junction comprising a reference magnetic layer having a reference magnetization, a tunnel barrier layer, and a storage magnetic layer including a first storage layer having a first storage magnetization, a second storage layer having a second storage magnetization, a storage coupling layer magnetically coupling the first storage magnetization antiparallel with the second storage magnetization, and an antiferromagnetic storage layer pinning, at a low temperature threshold, the storage magnetization of the storage layer being adjacent to the antiferromagnetic storage layer and freeing said storage magnetization at a high temperature threshold; in order to store a memory state, the method comprising: heating the magnetic tunnel junction to the high temperature threshold; applying a write magnetic field having a predetermined magnitude such as to orient the first and second storage magnetization; and cooling the magnetic tunnel junction to the low temperature threshold to freeze the first and second storage magnetizations in their written orientation; the write magnetic field being along the anisotropy axis of the storage layer in a first or second direction said second direction being opposite to the first direction; and in that said high temperature threshold comprises a first high temperature threshold or a third high temperature threshold and a second high temperature threshold, wherein: at said first high temperature threshold the write magnetic field is comprised between the coercive field and a spin-flop field of the storage magnetic layer, such that the first storage magnetization is oriented antiparallel to the second storage magnetization; at said second high temperature threshold the write magnetic field is above the spin-flop field of the storage magnetic layer, such that the first storage magnetization forms a predetermined angle, hereinafter termed (□) below 180° with respect to the second storage magnetization; and at said third high temperature threshold the write magnetic field is above a saturation field of the storage magnetic layer, such that the first storage magnetization is oriented parallel to the second storage magnetization; said method including the steps of: storing a first memory state (‘11’) in the storage magnetic layer wherein the first storage magnetization is oriented in said first direction by applying the first or third high temperature threshold and having the write magnetic field in said second direction; storing a second memory state (‘00’) in the storage magnetic layer wherein the first storage magnetization is oriented in said second direction by applying the first or third high temperature threshold and having the write magnetic field in said first direction; storing a third memory state (‘01’) in the storage magnetic layer wherein the first storage magnetization makes and angle of α/2 with the second direction by applying the second high temperature threshold and having the write magnetic field in said first direction; and storing a fourth memory state (‘10’) in the storage magnetic layer wherein the first storage magnetization makes and angle of 180°−α/2 with the second direction by applying the second high temperature threshold and having the write magnetic field in said second direction. |
