Spin-dependent single-electron tunnelling phenomena have been investigated in current-perpendicular-to-plane geometry for insulating granular systems. The sample structure consists of a 7-12-nm-thick Co-Al-O granular film sandwiched by the top and bottom electrodes. A very thin Al-O layer has been added between the bottom electrode and the granular film as a bottleneck of conductance, leading to the successful observation of Coulomb staircases in the current-bias voltage I-Vb characteristics. The Vb dependence of tunnel magnetoresistance (TMR) shows clear oscillatory behaviour associated with the Coulomb staircase. The TMR oscillation is interpreted as a phenomenal characteristic of spin-dependent single-electron tunnelling.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Acoustics and Ultrasonics
- Surfaces, Coatings and Films