Influence of Film Thickness on Magnetic Tunneling Junction Sensor with In-Plane/Out-of-Plane Sensing Capabilities

A magnetic tunnel junction (MTJ) sensor with out-of-plane or in-plane magnetized free layer to achieve a linear and hysteresis-free response is demonstrated. We show that two MTJ devices, with different magnetization arrangements in the free and reference layers, have different sensor responses. The sensor with out-of-plane magnetized free layer has in-plane sensing capability and that with the in-plane one has out-of-plane sensing capability. The present theoretical study based on the coherent rotation of the magnet moment in the free layer exhibits linear and nonlinear dependence of the sensitivity and sensing range, respectively, on the thickness of the free layer. These findings indicate that a sensor with high sensitivity can be achieved by precisely controlling the film thickness of the free layer.