Magnetic tunnel junction platforms for linear positioning and nanoscale displacement sensing

An array of magnetic tunnel junctions (MTJs), connected in a Wheatstone bridge, is characterized as a positioning sensor to detect spatial displacement of a magnetized object. To perform the experiment, the sensor was mounted on a fixed frame, and the magnet was installed on top of nano-positioning piezo-stage, operating in a closed-loop feedback circuit. The sensor signal was recorded in time domain, to detect displacement of the magnet, defined by commands to the stage. The positioning transfer curves were obtained for different orien-tations of magnetization with respect to the direction of the magnet displacement and the field sensing direction of the MTJs in the arrays. For configurations with linear transfer curve between positioning displacements and the sensor signal, the effects of magnet size, sensor pattern dimensions and interspace distance between the sensor and magnet positioning trajectories, are characterized. In the optimized experimental configuration, the displacement steps down to 10 nm were detected.

Automated summary

An array of magnetic tunnel junctions in a Wheatstone bridge is used as a positioning sensor to detect spatial displacement of a magnetized object. The sensor signal is recorded to determine the effects of various parameters on sensor performance, and an optimized experimental configuration allows for detection of displacement steps as small as 10 nm.