Disentangling complex current pathways in a metallic Ru/Co bilayer nanostructure using THz spectroscopy

TL;DR

This study uses THz spectroscopy and resistor network modeling to unravel complex current pathways in a Ru/Co bilayer nanostructure, revealing the transparency of the internal interface crucial for spintronic applications.

Contribution

It introduces a contact-free THz spectroscopy method combined with resistor network analysis to disentangle current pathways in metallic nanostructures, specifically addressing internal interface transparency.

Findings

Resolved complex current pathways in Ru/Co bilayer nanostructure

Quantified electronic transparency of the Ru/Co interface

Demonstrated a novel contact-free measurement approach

Abstract

Many modern spintronic technologies, such as spin valves, spin Hall applications, and spintronic THz emitters, are based on electrons crossing buried internal interfaces within metallic nanostructures. However, the complex current pathways within such nanostructures are difficult to disentangle using conventional experimental methods. Here, we measure the conductivity of a technologically relevant Ru/Co bilayer nanostructure in a contact-free fashion using THz time-domain spectroscopy. By applying an effective resistor network to the data, we resolve the complex current pathways within the nanostructure and determine the degree of electronic transparency of the internal interface between the Ru and Co nanolayers.