A thin-film magnetic device comprising, on a substrate, a composite assembly deposited by cathode sputtering and consisting of: - a first layer, made of a magnetic material with positive effective magnetic anisotropy, whose magnetisation in the absence of any electric or magnetic interaction is located outside the plane of said layer, and whose positive effective anisotropy per surface unit k eff2 including volume and interfacial contributions is given in CGS units by [(k v2 -2π M 2 2)e 2 + k s2], where: ▪ k v2 is the volume anisotropy of the first layer; ▪ M 2 is the magnetization of the first layer, ▪ e 2 is the thickness of the first layer; ▪ k s2 is the interfacial anisotropy oft he first layer; - a second layer, made of a material with negative effective anisotropy,, and whose negative effective anisotropy per surface unit k eff3 including volume and interfacial contributions is given in CGS units by [(k v3 -2π M 2 3) e 3 + k s3], where: ▪ k v3 is the volume anisotropy of the second layer; ▪ M 3 is the magnetization of the second layer, ▪ e 3 is the thickness of the second layer; ▪ k s3 is the interfacial anisotropy oft he first layer; said second magnetic layer made of permalloy, having a rate of spin polarization of the electrons of 50 to 60 % when an electric current flows through said layer in a direction perpendicular to its plane; - a third non-magnetic layer, in direct contact with the second magnetic layer with its interface opposed to the first magnetic layer, made of a material that is not polarising for electrons passing through this third non-magnetic layer, magnetic device characterized: - in that the first layer with effective anisotropy perpendicular to the plane of the layers is made of a material, alloy or multilayer of materials selected from the group comprising cobalt, platinum, iron, nickel, palladium, gold and copper; - in that the coupling energy per unit of surface area between the first magnetic layer and the second magnetic layer is at least twice the absolute value of the negative effective anisotropy of the second magnetic layer; - and in that said device also comprises means of causing an electric current to flow through its layers in a direction substantially perpendicular to their plane. - a first layer, made of a magnetic material with positive effective magnetic anisotropy, whose magnetisation in the absence of any electric or magnetic interaction is located outside the plane of said layer, and whose positive effective anisotropy per surface unit k eff2 including volume and interfacial contributions is given in CGS units by [(k v2 -2π M 2 2)e 2 + k s2], where: ▪ k v2 is the volume anisotropy of the first layer; ▪ M 2 is the magnetization of the first layer, ▪ e 2 is the thickness of the first layer; ▪ k s2 is the interfacial anisotropy oft he first layer; ▪ k v2 is the volume anisotropy of the first layer; ▪ M 2 is the magnetization of the first layer, ▪ e 2 is the thickness of the first layer; ▪ k s2 is the interfacial anisotropy oft he first layer; - a second layer, made of a material with negative effective anisotropy,, and whose negative effective anisotropy per surface unit k eff3 including volume and interfacial contributions is given in CGS units by [(k v3 -2π M 2 3) e 3 + k s3], where: ▪ k v3 is the volume anisotropy of the second layer; ▪ M 3 is the magnetization of the second layer, ▪ e 3 is the thickness of the second layer; ▪ k s3 is the interfacial anisotropy oft he first layer; said second magnetic layer made of permalloy, having a rate of spin polarization of the electrons of 50 to 60 % when an electric current flows through said layer in a direction perpendicular to its plane; ▪ k v3 is the volume anisotropy of the second layer; ▪ M 3 is the magnetization of the second layer, ▪ e 3 is the thickness of the second layer; ▪ k s3 is the interfacial anisotropy oft he first layer; - a third non-magnetic layer, in direct contact with the second magnetic layer with its interface opposed to the first magnetic layer, made of a material that is not polarising for electrons passing through this third non-magnetic layer, - in that the first layer with effective anisotropy perpendicular to the plane of the layers is made of a material, alloy or multilayer of materials selected from the group comprising cobalt, platinum, iron, nickel, palladium, gold and copper; - in that the coupling energy per unit of surface area between the first magnetic layer and the second magnetic layer is at least twice the absolute value of the negative effective anisotropy of the second magnetic layer; - and in that said device also comprises means of causing an electric current to flow through its layers in a direction substantially perpendicular to their plane.