Enhancement of magnetic field sensitivity by spin-transfer torque in in-plane magnetized superparamagnetic tunnel junctions

Abstract We measured the magnetic field dependence of superparamagnetic tunnel junctions (SMTJs) with in-plane magnetization and a diameter of 100 nm. A threefold enhancement in the slope of the probability curve was observed under the application of large currents. Based on these results, we propose a new type of highly sensitive tunnel magnetoresistance sensor utilizing SMTJs. Our findings reveal the limitations of the macro-spin model in capturing the actual behavior of SMTJs. These results advance our understanding of stochastic dynamics in nanoscale magnetic materials and highlight the potential of SMTJs for various spintronics applications, particularly in high-sensitivity magnetic sensing.