Large Magnetoresistance in Co/Ni/Co Ferromagnetic Single Electron Transistors

TL;DR

This study investigates magnetotransport properties of nano-scaled Co/Ni/Co single electron transistors, revealing significant tunneling magnetoresistance influenced by device size and bias conditions, with implications for spintronic applications.

Contribution

It presents the first detailed analysis of TMR behavior in Co/Ni/Co single electron transistors at low temperatures, highlighting the role of shape anisotropy and magnon excitations.

Findings

Observed TMR of about 18% at 1.8K.

TMR decreases rapidly with increasing bias.

Negative coercive fields linked to shape anisotropy.

Abstract

We report on magnetotransport investigations of nano-scaled ferromagnetic Co/Ni/Co single electron transistors. As a result of reduced size, the devices exhibit single electron transistor characteristics at 4.2K. Magnetotransport measurements carried out at 1.8K reveal tunneling magnetoresistance (TMR) traces with negative coercive fields, which we interpret in terms of a switching mechanism driven by the shape anisotropy of the central wire-like Ni island. A large TMR of about 18% is observed within a finite source-drain bias regime. The TMR decreases rapidly with increasing bias, which we tentatively attribute to excitation of magnons in the central island.