Skyrmions are circular magnetic domains of (sub-)micron size with increasing interest to the scientific community, considering to use them for information encoding. The aim of this thesis is to exploit the potential of skyrmions in a new way: developing a magnetic field sensor. Indeed, the response of skyrmions to the magnetic field perpendicular to the plane is quasi-linear with a very large slope and no hysteresis. Exploiting these properties in an all-electrical device would provide an integrated magnetometer, highly sensitive to the field oriented perpendicular to the sensor plane. Currently, the only integrated magnetometers sensitive to the perpendicular field are Hall probes whose detectivity is only 1µT/√Hz at low frequency. A skyrmion sensor is expected to achieve better performance, which we estimate to be 3nT/√Hz at 10 Hz, while limiting power consumption. This would make it a sensor of choice for the detection of very small homogeneous magnetic fields for space or geomagnetic applications or inhomogeneous fields for biomedical applications.
In this experimental thesis, we propose to (i) first electrically detect skyrmions by measuring the Hall effect signal in a patterned Hall cross, (ii) then embed the skyrmion layer in a magnetic tunnel junction in order to take advantage of its high tunnel magnetoresistance and (iii) finally develop a usable magnetometer targeting space or biomedical research applications.
The expected profile for the applicants is a Master-2 degree in a field related to condensed-matter physics, nanophysics with preference for basics in magnetism and/or spintronics.
More details here.