Tunneling spectroscopy probing magnetic and nonmagnetic electrodes in tunnel junctions

TL;DR

This paper uses tunneling spectroscopy to investigate magnetic and nonmagnetic electrodes in tunnel junctions, revealing differences in zero bias anomalies and material-dependent excitations, including magnons.

Contribution

It provides new insights into the excitation mechanisms in tunnel junctions with varying electrode magnetic properties using high-precision inelastic electron tunneling spectroscopy.

Findings

Zero bias anomaly differs in size and sign from magnetic junctions.

Material-dependent differences suggest magnon excitation.

Nonmagnetic and magnetic junctions show distinct bias dependence.

Abstract

Tunneling spectroscopy is applied to tunnel junctions with only one or no ferromagnetic electrode to study the excitation of quasi particles in magnetic tunnel junctions. The bias dependence is investigated with high accuracy by inelastic electron tunneling spectroscopy. Both types of junctions show a zero bias anomaly that is different in size and sign compared to magnetic tunnel junctions, i.e. junctions with two ferromagnetic electrodes. A pronounced difference is also found depending on the material that is probed by the tunneling electrons, which might be attributed to the excitation of magnons.