ELECTRICALLY TUNABLE HALL EFFECT CHARACTERISTICS IN ULTRA-THIN FEPT FILM.

Abstract

This thesis investigates the electrical tuning of Hall Effect characteristics in ultra-thin FePt film and explores its related mechanisms. First, the film properties of the MgO seed layer and FePt magnetic layer were optimized for the device fabrication. Next, the Hall voltage measurements were shown to change substantially and non-symmetrically under increasing gate voltages. For the Anomalous Hall Effect, the change in coercivity was 0.8% while the Hall Voltage Ratio (HVR) was 2227.4%. For Planar Hall Effect, the coercivity change was 1.1% while the HVR was 631.0%. Subsequently, the angular dependence behavior was analyzed and attributed to incoherent reversal processes or the transition of different Hall voltage components. The longitudinal voltage was then measured to be directly proportional to the Hall voltage. Three carrier transport-related coefficients were also extracted from the equations of Hall voltage versus current (VH-I) plots and deduced to be related to the electrical tuning effect.