Fe3O4 Thin Films can be Grown on hBN Substrate Without Affecting the Film Properties

Growing high-quality thin films of Fe₃O₄ is therefore important and has been achieved on a variety of stiff substrates. However, achieving flexible devices is regarded as an important goal in the development of electronics, and this requires films that can be easily transferred onto flexible substrates.

hBN is a physically and chemically stable material, making it an excellent choice for growing Fe₃O₄ films. hBN has layers that associate through der Waals interactions, which are weaker than ionic and covalent bonds, making them easier to manipulate and move.

"Generally, if you grow crystals of one material on another crystal, the way their atoms are arranged has to match or the film will grow with defects," explains study first author Shingo Genchi. "However, owing to the van der Waals interactions of hBN, high-quality Fe₃O₄ could be grown despite there being a mismatch, showing the potential of hBN as a universal transferrable substrate."

The properties of the Fe₃O₄ film grown on hBN were investigated, and it was found that the transition temperature from an insulating to metallic material was not affected by hBN. The temperature of the change was also found to be the same for Fe₃O₄ films with different thicknesses.

The film was transferred onto a SiO₂/Si substrate and again retained its properties, demonstrating the versatility of the hBN approach.

"Our high-quality Fe₃O₄ films are an exciting next step in the development of spintronic materials," says study corresponding author Hidekazu Tanaka. "We believe that our films will make an important contribution to flexible devices."

The article, "Prominent Verway transition of Fe₃O₄ thin films grown on transferable hexagonal boron nitride," was published in ACS Applied Electronic Materials at DOI: https://doi.org/10.1021/acsaelm.1c00803