Stabilizing Metastable Rare-Earth Ferrites on (111) Platinum via an Iron Oxide Interlayer

TL;DR

Researchers stabilized a rare-earth ferrite material on platinum using an iron oxide interlayer, improving its potential for advanced electronic devices.

Contribution

A novel interlayer design enables stabilization of h-ScFeO3 on conductive (111) platinum substrates, overcoming thickness and strain limitations.

Findings

Films of h-ScFeO3 on (111) platinum show no secondary phases and improved structural quality.

The interlayer reduces epitaxial strain and allows structural distortion in the first layers of h-ScFeO3.

This approach expands viable substrates for metastable materials and enables improper ferroelectricity.

Abstract

The metastable P63
cm phase of ScFeO3 (h-ScFeO3) is a
multiferroic
material, but instability on conductive substrates limits the development
of next-generation memory and magnetoelectric sensors. Unfortunately,
stabilization approaches developed for insulating substrates, such
as sapphire, do not translate directly to conductive substrates. In
this work, we demonstrate how interlayer design preferentially stabilizes
h-ScFeO3 on (111) platinum via molecular beam epitaxy while
simultaneously enhancing key figures of merit. We developed a process
to deposit a (111) wüstite-like interlayer with a metastable
Fe3+ oxidation state to target h-ScFeO3. The
films are solely (0001) oriented h-ScFeO3 without any measured
secondary phases. Rocking curves of the 0004 h-ScFeO3 peak
have a full width at half-maximum of 0.06°, an improvement compared
to films deposited without this interlayer approach. A further indication
of strain reduction in these films is structural distortion in the
first layers of h-ScFeO3, overcoming the critical thickness
limit in h-ScFeO3. Designing interlayers to reduce epitaxial
strain and target specific phases expands the viable substrates for
metastable materials and overcomes the thickness limits for improper
ferroelectricity.

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