Strain-Engineered Tetragonal Phase and Ferroelectricity in GdMnO3 Thin Films Grown on SrTiO3 (001)

Abstract

A previously unreported tetragonal phase has been discovered in a epitaxially strained GdMnO3 thin films deposited on (001)-oriented SrTiO3 substrates by radio frequency (RF) magnetron sputtering. The tetragonal axis of the films grown up to a 35 nm thickness is perpendicular to the film surface and the basal lattice parameters are imposed by the cubic structure of the substrate. Furthermore, the emergence of a spontaneous electric polarization below ~32 K points to the stabilization of an improper ferroelectric phase at low temperatures, which is not observed in bulk GdMnO3. This work shows how strain engineering can be used to tailor the structure and properties of strongly correlated oxides.

Orthorhombic GdMnO3 Epitaxial Thin Film Grown onto SrTiO3 (110)

“…GMO polycrystalline targets were prepared following the procedure described elsewhere [11]. Polished (110)-oriented SrTiO3 substrates (STO(110)) were previously cleaned before deposition in ultrasonic baths and dried using N2 flow.…”

“…In-plane specific magnetization measurements were carried out using a SQUID magnetometer, with a resolution better than 5x10 -7 emu. The complex electric permittivity was measured in the 1 kHz -1 MHz frequency range with an HP4284A impedance analyser, under a 50 V/cm ac electric field [11]. 50 gold interdigital electrodes (IDEs), with 7 mm length, 20 μm width, 20 μm interspacing and depth of about 90% of the thickness of the deposited film, were used for the measurements [11].…”

“…Here we highlight that ferroelectricity was achieved below 30 and 75 K on orthorhombic GMO thin-films with 10 and 110 nm, deposited by pulsed laser deposition onto (010)-YAlO3 and (001)-SrTiO3 substrates, respectively [9,10]. Recently, the study of epitaxially strained GMO thin-films deposited on (001)-SrTiO3 substrate by RF magnetron sputtering, conveyed an unprecedently reported tetragonal structure at room temperature and ferroelectric below 32 K, up to 35 nm thick films [11]. The emergence of a spontaneous electric polarization in these films reveal the stabilization of a low temperature improper ferroelectric phase, not observed in bulk GMO.…”

Estudio de materiales de interés ambiental: celdas fotoelectroquímicas y oxinitruros ferroeléctricos

“…En particular, el SrTiO 3 (STO) ha generado un notable interés debido a su capacidad para servir como sustrato para crecimiento epitaxial de alta calidad de superconductores de alta temperatura y también para películas delgadas a base de óxidos. Este compuesto, que es cúbico a temperatura ambiente con un parámetro de red de 3,905 Å, resulta altamente adecuado como sustrato para el crecimiento de una amplia variedad de otros óxidos, debido a sus propiedades estructurales y a su compatibilidad con algunos materiales como aluminato de lantano (LaAlO 3 ) [72], rutenato de estroncio (SrRuO 3 ), manganita a base de gadolinio (GdMnO 3 ) [73], zirconato de calcio (CaZrO 3 ) [44], niobato de estroncio (SrNbO 3 ) [74], entre otros. Eso lo convierte en una opción favorable para el desarrollo de nuevos compuestos ferroeléctricos.…”