Tunnel magnetoresistance oscillations associated with Coulomb staircases in insulating granular systems

摘要

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-V-b characteristics. The V-b 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. [References: 14]