Electric control of magnetic skyrmions for sensing applications

Published : 15 July 2019

Skyrmions are spin textures through which the magnetization follows a cycloid, rotating in either direction, which defines the chirality of the skyrmion. These topological solitons are currently of considerable interest both for the underlying physics and for their application potential, as they are movable by an electric current. In addition, the ability to adjust the interface magnetic properties by a gate voltage allows control of spintronics devices with low power consumption and provides an additional versatile, local and dynamic degree of freedom.

In this context, we have recently shown that a gate voltage can not only create and erase skyrmions, but also modify the Dzyaloshinskii-Moriya interaction (DMI) responsible for skyrmions’ stability. Our experiments have revealed a new origin of DMI, which may allow to control the sign of DMI by gate voltage.

In this experimental thesis, we aim to observe this change in the sign of DMI, which will produce a change in chirality of the skyrmions. This breakthrough would open up new possibilities for the manipulation of skyrmions, as a change in chirality would reverse the direction of current induced motion.

In addition, these chiral magnetic configurations being very sensitive to an external magnetic field, magnetic sensor applications are considered. Furthermore, we have observed that the sensitivity of such sensors could be modulated by a gate voltage. We will therefore also focus on:

– controlling the different contributions to the DMI by playing with the materials;

– optimizing the temperature stability of the skyrmions and their sensitivity to gate voltage, in order to increase the sensitivity of the sensor and its electrical modulation ;

– characterizing the electrical signature of skyrmions using magneto-optical microscopy coupled with transport measurements.

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