Miniaturized magnetostrictive strain sensors for novel applications of atomic force microscopy

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Based on the results of the first application period we will use magnetostrictive tunneling structures as highly sensitive strain sensors to enable new applications of atomic force microscopy with self-sensing cantilevers. With this aim, the miniaturization of the strain-sensitive tunneling structures will be pushed forward to submicron scales and supported by micromagnetic simulations. The comparison between simulation and experiment will contribute to the understanding of the magnetization reversal in mechanically stressed magnetostrictive structures, finally leading to an increased control of their magnetization configurations. This in turn has a direct impact on the long-term stability of the sensors.Through the planned development of the layer system of tunneling structures, we aim on the one hand on the increase of sensitivity and signal to noise ratio. On the other hand, an internal magnetic bias field will be implemented into the layer system, in order to eliminate the need for an external bias field to measure at an optimal operating point. For this purpose we will apply the concept of a sensor electrode coupled to an antiferromagnetic layer sensor, which has been very successful in solving a similar problem with magnetoelectric magnetic field sensors.With these new self-sensing cantilevers we will carry out atomic force microscopy experiments under ambient conditions, in vacuum, and in liquids on different sample systems. Our focus is on applications where conventional optical detection system of conventional AFMs can be detrimental. Furthermore, we will build and analyze cantilevers with multiple strain sensors for friction force and multi-frequency measurements.