Efficient, high-density, carbon-based spinterfaces

TL;DR

This study demonstrates that highly spin-polarized interfaces can form between ferromagnetic cobalt and simple carbon atoms, revealing a generic, molecule-agnostic pathway for spintronics applications at room temperature.

Contribution

It shows that dense, semiconducting carbon films on cobalt create highly spin-polarized interface states, broadening the scope of organic spinterfaces for spintronics.

Findings

High spin polarization at room temperature at cobalt/carbon interfaces

Formation of dense semiconducting carbon films with low band gap

Spin-polarized states mainly from sp2-bonded carbon atoms

Abstract

The research field of spintronics has sought, over the past 25 years and through several materials science tracks, a source of highly spin-polarized current at room temperature. Organic spinterfaces, which consist in an interface between a ferromagnetic metal and a molecule, represent the most promising track as demonstrated for a handful of interface candidates. How general is this effect? We deploy topographical and spectroscopic techniques to show that a strongly spin-polarized interface arises already between ferromagnetic cobalt and mere carbon atoms. Scanning tunneling microscopy and spectroscopy show how a dense semiconducting carbon film with a low band gap of about 0.4 eV is formed atop the metallic interface. Spin-resolved photoemission spectroscopy reveals a high degree of spin polarization at room temperature of carbon-induced interface states at the Fermi energy. From both our previous study of cobalt/phthalocyanine spinterfaces and present x-ray photoemission spectroscopy studies of the cobalt/carbon interface, we infer that these highly spin-polarized interface states arise mainly from sp2-bonded carbon atoms. We thus demonstrate the molecule-agnostic, generic nature of the spinterface formation.