Symmetry-selected spin-split hybrid states in C$_{60}$/ferromagnetic interfaces

TL;DR

This study uses first-principles calculations to explore how the adsorption geometry and substrate type influence spin-polarized hybrid states in C60/ferromagnetic interfaces, informing spintronic device design.

Contribution

It systematically analyzes the impact of surface crystallography and molecular orientation on spin polarization in C60/ferromagnetic interfaces, revealing optimal conditions for high spin polarization.

Findings

Large spin-polarization occurs only on bcc-(001) surfaces with pentagonal ring adsorption.

Adsorption geometry and substrate symmetry strongly influence induced spin polarization.

Experimental STM measurements confirm the importance of substrate and molecular conformation.

Abstract

The understanding of orbital hybridization and spin-polarization at the organic-ferromagnetic interface is essential in the search for efficient hybrid spintronic devices. Here, using first-principles calculations, we report a systematic study of spin-split hybrid states of C$_{60}$ deposited on various ferromagnetic surfaces: bcc-Cr(001), bcc-Fe(001), bcc-Co(001), fcc-Co(001) and hcp-Co(0001). We show that the adsorption geometry of the molecule with respect to the surface crystallographic orientation of the magnetic substrate as well as the strength of the interaction play an intricate role in the spin-polarization of the hybrid orbitals. We find that a large spin-polarization in vacuum above the buckyball can only be achieved if the molecule is adsorbed upon a bcc-(001) surface by its pentagonal ring. Therefore bcc-Cr(001), bcc-Fe(001) and bcc-Co(001) are the optimal candidates. Spin-polarized scanning tunneling spectroscopy measurements on single C$_{60}$ adsorbed on Cr(001) and Co/Pt(111) also confirm that both the symmetry of the substrate and of the molecular conformation have a strong influence on the induced spin polarization. Our finding may give valuable insights for further engineering of spin filtering devices through single molecular orbitals.