Effective Resistance Mismatch and Magnetoresistance of a CPP-GMR system with Current-Confined-Paths

TL;DR

This paper theoretically investigates how current-confined-path structures enhance magnetoresistance in CPP-GMR systems, revealing an optimal contact width for maximum MR ratio based on resistance matching.

Contribution

It introduces a theoretical framework for analyzing CCP structures in CPP-GMR systems and identifies the contact width that maximizes MR ratio using resistance matching principles.

Findings

MR ratio is enhanced by CCP structure.

Existence of an optimal contact width for maximum MR.

Effective resistance matching explains the optimal contact width.

Abstract

We theoretically study the magnetoresistance of a CPP-GMR system with current confined paths (CCP) in the framework of Valet-Fert theory. The continuity equations for charge and spin currents are numerically solved with the three-dimensional CCP geometry by use of finite element method. It is confirmed that the MR ratio is enhanced by the CCP structure, which is consistent with the experimental results. Moreover, we find that there exists a certain contact width which maximize the MR ratio. We show that the contact width which maximize the MR ratio is well described by the effective resistance matching.