Thin-film encapsulation of the air-sensitive organic-based ferrimagnet vanadium tetracyanoethylene

Abstract

The organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]x∼2) has demonstrated potential for use in both microwave electronics and spintronics due to the combination of high temperature magnetic ordering (TC > 600 K), extremely sharp ferromagnetic resonance (peak to peak linewidth of 1 G), and low-temperature conformal deposition via chemical vapor deposition (deposition temperature of 50 °C). However, air-sensitivity leads to the complete degradation of the films within 2 h under ambient conditions, with noticeable degradation occurring within 30 min. Here, we demonstrate encapsulation of V[TCNE]x∼2 thin films using a UV-cured epoxy that increases film lifetime to over 710 h (30 days) as measured by the remanent magnetization. The saturation magnetization and Curie temperature decay more slowly than the remanence, and the coercivity is unchanged after 340 h (14 days) of air exposure. Fourier transform infrared spectroscopy indicates that the epoxy does not react with the film, and magnetometry measurements show that the presence of the epoxy does not degrade the magnetic properties. This encapsulation strategy directly enables a host of experimental protocols and investigations not previously feasible for air-sensitive samples and lays the foundation for the development of practical applications for this promising organic-based magnetic material.

Controlling Ferromagnetic Ground States and Solitons in Thin Films and Nanowires Built from Iron Phthalocyanine Chains

“…It would be preferable to use organic layers for injection, transport and detection as here there would be mechanically and chemically compatible interfaces suited for use with flexible substrates. Currently, however, there are very few molecular magnets stable at high temperature, with the exception of the V(TCNE) x family, associated with delicate processing and stability, although recent progress on encapsulation could help the integration for applications …”

Low loss spin wave resonances in organic-based ferrimagnet vanadium tetracyanoethylene thin films

“…40 Because of its air-sensitivity, the film is encapsulated using a technique that preserves the magnetic order for over one month under ambient condition. 41 The technique requires applying an epoxy (purchased from Ossila) to the film surface. A glass cover slide is placed over the epoxy and pressed down firmly to spread the epoxy across the film surface and edges to isolate the film from the air, and to provide mechanical protection for the sample.…”

Magnetic ordering in a vanadium-organic coordination polymer using a pyrrolo[2,3-d:5,4-d′]bis(thiazole)-based ligand

“…40 As observed with other polycyanoorganic-based vanadium coordination polymers, 8 is air-sensitive and should be stored in a sealed tube under inert atmosphere to minimize the degradation of magnetic properties, or encapsulated if synthesized in thin-lm form. 6 Single crystal X-ray analysis of the parent 4-n-hexyl-4H-pyrrolo[2,3-d:5,4-d 0 ]bis(thiazole), its 2,6-diiodo derivative and ligand 7 indicate presence of the disorder in hexyl chains and a linear arrangement between the substituents in positions 2 and 6. The discovery of magnetic ordering in compound 8, despite the exible alkyl groups and the larger size of the ligand in comparison with majority of the previously studied organic polycyano compounds, demonstrates the suitability of the new class of tricyclic organic ligands, and potentially a large variety of other tetracyano quinoidal systems with extended cores, for the preparation of novel hybrid magnets.…”

“…2). The hexyl chain in this molecule is perpendicular to the tricyclic core with dihedral angle of 89.83 (6) . The dihedral angle between the two thiazole rings is 1.7(1) indicating a nearly planar tricyclic core.…”

“…2 The application of V$(TCNE) x as a spin injection/detection layer in hybrid devices 3 and demonstration of material suitability for high-quality magnonic circuits 4,5 indicate that metal-organic hybrid materials are competitive with traditional inorganic magnetic materials. Further, the air-sensitivity common to metal-ligand materials can be addressed by encapsulation, 6 directly enabling their use in devices that operate under ambient conditions.…”