Magnetoresistive sensor element having compensated temperature coefficient of sensitivity and method for manufacturing said element

A magnetoresistive sensor element comprising:

• a reference layer having a pinned reference magnetization;
• a sense layer having a free sense magnetization comprising a stable vortex configuration having a core reversibly movable in accordance to an external magnetic field to be measured;
• a tunnel barrier layer between the reference layer and the sense layer, the tunnel barrier layer comprising an insulating material;
• wherein the sense layer comprises a first ferromagnetic sense portion in contact with the tunnel barrier layer and a second ferromagnetic sense portion in contact with the first ferromagnetic sense portion;
• and
• wherein the second ferromagnetic sense portion comprises a dilution element in a proportion such that a temperature dependence of a magnetic susceptibility of the sense layer substantially compensates a temperature dependence of a tunnel magnetoresistance (TMR) of the magnetoresistive sensor element.

A magnetoresistive sensor for sensing a 1D external magnetic field, comprising a plurality of magnetoresistive sensor elements, each magnetoresistive sensor element comprising:

• a reference layer having a pinned reference magnetization;
• a sense layer having a free sense magnetization comprising a stable vortex configuration having a core reversibly movable in accordance to an external magnetic field to be measured;
• a tunnel barrier layer between the reference layer and the sense layer, the tunnel barrier layer comprising an insulating material;
• wherein the sense layer comprises a first ferromagnetic sense portion in contact with the tunnel barrier layer and a second ferromagnetic sense portion in contact with the first ferromagnetic sense portion;
• and
• wherein the second ferromagnetic sense portion comprises a dilution element in a proportion such that a temperature dependence of a magnetic susceptibility of the sense layer substantially compensates a temperature dependence of a tunnel magnetoresistance (TMR) of the magnetoresistive sensor element.

Method for manufacturing the magnetoresistive sensor element, wherein the magnetoresistive sensor element comprises:

• a reference layer having a pinned reference magnetization;
• a sense layer having a free sense magnetization comprising a stable vortex configuration having a core reversibly movable in accordance to an external magnetic field to be measured;
• a tunnel barrier layer between the reference layer and the sense layer, the tunnel barrier layer comprising an insulating material;
• wherein the sense layer comprises a first ferromagnetic sense portion in contact with the tunnel barrier layer and a second ferromagnetic sense portion in contact with the first ferromagnetic sense portion;
• and
• wherein the second ferromagnetic sense portion comprises a dilution element in a proportion such that a temperature dependence of a magnetic susceptibility of the sense layer substantially compensates a temperature dependence of a tunnel magnetoresistance (TMR) of the magnetoresistive sensor element,
• the method comprising, for a plurality of temperatures and concentrations of the dilution element:
• measuring an electrical conductance of the magnetoresistive sensor element as a function of the external magnetic field for a plurality of temperatures, such as to obtain a plurality of measured conductance curve for each temperature;
• calculating a value of TMR of the magnetoresistive sensor element from the plurality of conductance curves, such as to determine the temperature dependence of TMR;
• and
• measuring a magnetization of the sense layer, such as to determine the temperature dependence of the magnetic susceptibility of the sense layer;
• and
• determining the proportion of the transition metal element for which the temperature dependence of TMR substantially compensates the temperature dependence of the magnetic susceptibility.