posted on 2023-01-04, 09:57authored byBinjie Chen, Tsukasa Katayama
Hexagonal rare-earth ferrites (h-RFeO3) are promising multiferroic materials owing
to the
spontaneous magnetization, high ferroelectric transition temperature,
and fascinating features provided by strong magnetoelectric coupling.
However, h-RFeO3 is metastable,
and its synthetic methods are limited, particularly when ionic size
of R is large. One of useful synthesis methods is
epitaxial thin-film growth on single-crystal substrates, because the
metastable phase is stabilized by the lattice match between h-RFeO3 and the substrate. Compared
to single-crystal substrates, glass substrates are more cost-effective.
However, films on glass tend to consist of a thermodynamically stable
phase owing to the amorphous nature of glass substrates. Herein, we
report that a h-RFeO3 pure phase can be
obtained as thin film even on glass substrates. The metastable phase
was formed owing to the nonequilibrium synthesis process of pulsed
laser deposition. The obtained h-RFeO3 thin films on glass with R = Dy, Er, and Lu exhibited
weak ferromagnetism with Néel temperatures of 120–140
K. Furthermore, a clear magnetic phase transition from weak ferromagnetic
to antiferromagnetic phase was observed in the h-ErFeO3 films. Additionally, piezoelectric force microscopy measurements
exhibited the ferroelectricity of the film at room temperature. These
results provide a convenient synthesis method of a pure phase multiferroic h-RFeO3 system.