Recovering ferromagnetic metal surfaces to fully exploit chemistry in molecular spintronics

Abstract

Organic spintronics is a new emerging field that promises to offer the full potential of chemistry to spintronics, as for example high versatility through chemical engineering and simple low cost processing. However, one key challenge that remains to be unlocked for further applications is the high incompatibility between spintronics key materials such as high Curie temperature Co, Ni, Fe (and their alloys) and wet chemistry. Indeed, the transition metal proneness to oxidation has so far hampered the integration of wet chemistry processes into the development of room temperature organic spintronics devices. As a result, they had mainly to rely on high vacuum physical processes, restraining the choice of available organic materials to a small set of sublimable molecules. In this letter, focusing on cobalt as an example, we show a wet chemistry method to easily and selectively recover a metallic surface from an air exposed oxidized surface for further integration into spintronics devices. The oxide etching process, using a glycolic acid based solution, proceeds without increasing the surface roughness and allows the retrieval of an oxygen-free chemically active cobalt layer. This unlocks the full potential of wet chemistry processes towards room temperature molecular spintronics with transition metals electrodes. We demonstrate this by the grafting of alkylthiols self-assembled monolayers on recovered oxidized cobalt surfaces. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx.

Combined spin filtering actions in hybrid magnetic junctions based on organic chains covalently attached to graphene

“…Indeed, oxidation occurs at the surface and it is widely known to quench the emerging spin polarization. 51 Few technological solutions were investigated such as the use of oxide materials as electrodes, 52,53 surface pre-cleaning with an appropriate acid 23 or a parallel growth/surface reduction by electrochemistry. 22,54 Graphene protection was also shown to allow preserving a metallic interface in ambient conditions as demonstrated earlier.…”

Spontaneous growth of 2D coordination polymers on functionalized ferromagnetic surfaces

“…We have prepared SAMs of alkanethiols (C n H 2 n +1 SH, C n S, n = 14, 16, and 18) on cobalt and permalloy (Py) under an inert atmosphere using our previously described method 12. The quality of the SAMs was determined using AFM and contact angle (CA) measurements (Table S1 and Fig.…”

“…As a part of our investigation on the fabrication of molecular-based spintronic devices, we have prepared hybrid interfaces formed by ferromagnetic metal surfaces functionalized with SAMs of alkanethiol molecules 12. Notice that the chemical modification of metallic ferromagnetic surfaces, like cobalt, iron, nickel and their alloys, such as permalloy (NiFe), currently represents a technological challenge.…”

Hybrid Interfaces in Molecular Spintronics

“…However, this oxide layer is not an ideal scenario for spin transport processes. In an ulterior paper the development of an efficient protocol to remove this oxide layer was reported . It involves a chemical treatment with glycolic acid under inert atmosphere, giving rise to an oxide free active metallic surface that can be successfully functionalized by alkanethiol SAMs.…”