Sujet de stage / Master 2 Internship

The aim of the internship is to study the stray fields emitted by giant magnetoresistance (GMR) sensors by combining magnetometry, magnetotransport and magnetic mapping measurements, and to optimize the structure of the sensors in order to implement them in high-sensitivity magnetic microscopes.

A giant magnetoresistance sensor is schematically composed of two magnetic layers separated by a spacer (M1/E/M2). One of the layers (M1) is free to follow the magnetic field to be detected while the magnetization of the other layer (M2) is fixed. The effect of giant magnetoresistance or tunneling induces a variation of the resistance according to the angle between the magnetizations of the 2 layers allowing a detection of the field by the variation of resistance.

The aim of the internship is to study and reduce the stray fields emitted by the magnetizations of the two magnetic layers. Indeed, these stray fields can create disturbances on the system to be studied, in the case of magnetic mapping for example, and make the performance of GMRs strongly dependent on their size.

During the internship, several techniques will be used to measure the stray fields of the sensors: magnetometry, magnetotransport and magnetic mapping measurements. Sensor stray fields can be reduced by working on the structure and stacking of the magnetic layers, which is in practice more complex than the one presented schematically (M1/E/M2). The depositions will be made by sputtering, then the structures will be fabricated by UV lithography in order to be able to characterize them.