FeCoCp3 Molecular Magnets as Spin Filters

TL;DR

This study investigates a Co-Fe based molecular magnet with high magnetic anisotropy, demonstrating its potential as an efficient spin filter in molecular spintronics, while highlighting the impact of magnetic excitations and thermoelectric effects on performance.

Contribution

The paper introduces a new FeCoCp3 molecule with enhanced magnetic anisotropy and spin-filtering capabilities, emphasizing the importance of inelastic and thermoelectric effects in molecular spintronics.

Findings

High magnetic anisotropy improves spin-filtering capacity.

Magnetic excitations reduce spin polarization during transport.

Thermoelectric effects can suppress spin polarization.

Abstract

Metallorganic molecules have been proposed as excellent spin filters in molecular spintronics because of the large spin-polarization of their electronic structure. However, most of the studies involving spin transport, have disregarded fundamental aspects such as the magnetic anisotropy of the molecule and the excitation of spin-flip processes during electron transport. Here, we study a molecule containing a Co and an Fe atoms stacked between three cyclopentadienyl rings that presents a large magnetic anisotropy and a S=1. These figures are superior to other molecules with the same transition metal, and improves the spin-filtering capacities of the molecule. Non-equilibrium Green's functions calculations based on density functional theory predict excellent spin-filtering properties both in tunnel and contact transport regimes. However, exciting the first magnetic state drastically reduces the current's spin polarization. Furthermore, a difference of temperature between electrodes leads to strong thermoelectric effects that also suppress spin polarization. Our study shows that in-principle good molecular candidates for spintronics need to be confronted with inelastic and thermoelectric effects.