In industry, magnetic field sensors on the basis of the giant and even more the tunneling magnetoresistance effects (GMR, TMR) are still often treated as “new technology”, despite the fact that such are used in applications for more than 20 years now. However, this view is comprehensible when the operational environment is taken into account: GMR and TMR technology was first introduced in the data storage business as read heads in hard disk drives. It was continuously developed throughout the last decades to measure weakest magnetic stray fields from ever decreasing bits. On the one hand, data storage is a consumer application with a rated temperature operation range hardly exceeding 40°C. Moreover, the package is gas-tight and magnetically shielded, and thus, the sensor environment is perfectly controlled to allow a reliable operation. On the other hand, the sensor principle is the simplest as being used as a switch, where the magnetic properties, especially hysteresis, is not critical. Nowadays, applications as switch as well as angular sensors are commercialized in automotive and industrial environments, too. For those, the development mainly focused on sensor architecture stability, and the temperature requirements with a reliable operation up to 150°C were met finally. On the contrary, use cases, such as distance and current sensors, where the magnetic field sensor is not utilized in magnetic saturation but where the magnetization reversal of the sensing layer over the whole sensitive field range defines the characteristic, are still lacking. That is due to the present lack of a reliable control of the microstructure’s magnetic properties on wafer-scale, namely hysteresis, offset and non-linearity, where R&D is still required on the sensor microstructure architecture. Furthermore, magnetic functionalization by, e.g. laser annealing, and the application specific system design including packaging and the exact design of sensor elements as well as the reference magnetic field are R&D tasks of the near future.

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