In the context of the search for environment-respectful, lead- and bismuth- free chemical compounds for devices such as actuators, SnTiO3 (ST) is investigated from first principles within DFT. Full geometry optimization provides a stable tetragonal s
tructure relative to cubic one. From the equation of state the equilibrium volume of SnTiO3 is found smaller than ferroelectric PbTiO3 (PT) in agreement with a smaller Sn2+ radius. While ionic displacements exhibit similar trends between ST and PT a larger tetragonality (c/a ratio) for ST results in a larger polarization, PST = 1.1 C.m2. The analysis of the electronic band structure detailing the Sn-O and Ti-O interactions points to a differentiated chemical bonding and a reinforcement of the covalent bonding with respect to Pb homologue.
We have investigated the effects of substituting In for Mn on the antiferromagnetic phase transition in YMnO3 using magnetic, dielectric, and specific heat measurements. We prepared a set of isostructural phase pure hexagonal YMn$_{1-x}$In$_{x}$O$_{3
}$ samples having x=0 to x=0.9, which exhibit a systematic decrease of the antiferromagnetic ordering temperature with increasing In content. The multiferroic phase, which develops below TN, appears to be completely suppressed for x$geq$0.5 in the temperature range investigated, which can be attributed solely to the dilution of magnetic interactions as the crystal structure remains hexagonal. Similar to previous reports, we find an enhancement of the magnetocapacitive coupling on dilution with non-magnetic ions.
Epitaxial LaRh1/2Mn1/2O3 thin films have been grown on (001)-oriented LaAlO3 and SrTiO3 substrates using pulsed laser deposition. The optimized thin film samples are semiconducting and ferromagnetic with a Curie temperature close to 100 K, a coercive
field of 1200 Oe, and a saturation magnetization of 1.7muB per formula unit. The surface texture, structural, electrical, and magnetic properties of the LaRh1/2Mn1/2O3 films was examined as a function of the oxygen concentration during deposition. While an elevated oxygen concentration yields thin films with optimal magnetic properties, slightly lower oxygen concentrations result in films with improved texture and crystallinity.
