Spin-dependent tunneling junctions with superparamagnetic sensing layers

Spin-dependent tunneling (SDT) junctions with superparamagnetic (SPM) sensing layers have been made using sputtering deposition and photolithography fabrication techniques. The SPM-SDT junctions have zero hysteresis with reasonable sensitivity, and the output signal is bipolar relative to the external magnetic field without using any biasing-an inherent advantage in using a unidirectional pinned layer and an in-plane-isotropic SPM free layer in the SDT structure. This novel SPM-SDT junction is the first of its kind ever reported and offers great potential for commercial applications. The SPM-SDT devices are especially suitable for low-power and low-field applications such as solid-state compassing, magnetic medium detection, nondestructive evaluation, biomedical sensing, and mobile electronics device applications.