Work

Observation of magnetoresistance effect in Ni78Fe22/tris-(8-hydroxyquinoline) erbium (Erq3)/FeCo organic spin valves

Year: 2025

Type: article

Abstract: • We focus on tris-(8-hydroxyquinoline) erbium (Erq 3 ) for use in spintronic devices. • Ni 78 Fe 22 (Py)/Erq 3 /FeCo organic spin valves (OSVs) are successfully fabricated. • The fabricated OSVs consist of the Erq 3 layer with well-defined interfaces. • Both parallel and antiparallel magnetization states can be achieved in the OSVs. • MR effect is observed in Erq 3 -based OSVs for the first time. Molecular spintronics has attracted significant interest because organic molecules composed of light elements exhibit long spin diffusion lengths and are suitable as spin transport layers. Recently, a large magnetoresistance (MR) effect has been observed in devices using molecules composed of atoms with small nuclear spins. Here, we focus on tris-(8-hydroxyquinoline) erbium (Erq 3 ), in which Al is replaced by Er in tris-(8-hydroxyquinoline) aluminum (Alq 3 ). The nuclear spin of Al is 5/2, whereas that of Er is 0. A small nuclear spin can provide a weak hyperfine interaction, leading to the suppression of spin scattering. In this study, we fabricate Ni 78 Fe 22 (Py)/Erq 3 /FeCo crossbar organic spin valves (OSVs) and investigate their spin transport properties. Using sputtering, thermal evaporation and lithography techniques, we have successfully fabricated Py/Erq 3 /FeCo OSVs with a 29-nm-thick Erq 3 layer, which exhibits well-defined interfaces and long-range homogeneity over the entire region. Moreover, the MR effect is observed in accordance with the magnetization states of the OSVs. This indicates that we can successfully detect a spin signal through an Erq 3 layer with a thickness of 29 nm. These results may open new avenues for the development of organic spintronics based on the nuclear spins of molecules.

Source: Journal of Magnetism and Magnetic Materials

DOI: 10.1016/j.jmmm.2025.173465