Titanates with the perovskite structure, including ferroelectrics （e.g., BaTiO3） and ferromagnetic ones （e.g., YTiO3）, are important functional materials. Recent theoretical studies predicted multi- ferroic states...Titanates with the perovskite structure, including ferroelectrics （e.g., BaTiO3） and ferromagnetic ones （e.g., YTiO3）, are important functional materials. Recent theoretical studies predicted multi- ferroic states in strained EuTiO3 and titanate superlattices, the former of which has already been experimental confirmed. Here, a first-principles calculation is performed to investigate the struc- tural, magnetic, and electronic properties of Y half-substituted LaTiO3. Our results reveal that the magnetism of Yo.sLao.5TiO3 sensitively depends on its structural details because of the inher- ent phase competition. The lowest energy state is the ferromagnetic state, resulting in 0.25 μB/Ti. Furthermore, some configurations of Y0.500La0.5TiO3 exhibit hybrid improper polarizations, which can be significantly affected by magnetism, resulting in the multiferroic properties. Because of the quenching disorder of substitution, the real Y0.5La0.5TiO3 material with random A-site ions may exhibit interesting relaxor behaviors.展开更多
PbTiO3 is a simple but very important ferroelectric oxide that has been extensively studied and widely used in various technological applications. However, most previous studies and applications were based on the bulk...PbTiO3 is a simple but very important ferroelectric oxide that has been extensively studied and widely used in various technological applications. However, most previous studies and applications were based on the bulk material or the conventional [001]-orientated films. There are few studies on PbTiO3 films grown along other crystalline axes. In this study, a first-principles calculation was performed to compute the polarization of PbTiO3 films strained by SrTiO3 and LaAlO3 substrates. Our results show that the polarization of PbTiO3 films strongly depends on the growth orientation as well as the monoclinic angles. Further, it is suggested that the ferroelectricity of PbTiO3 mainly depends on the tetragonality of the lattice, instead of the simple strain.展开更多
文摘Titanates with the perovskite structure, including ferroelectrics （e.g., BaTiO3） and ferromagnetic ones （e.g., YTiO3）, are important functional materials. Recent theoretical studies predicted multi- ferroic states in strained EuTiO3 and titanate superlattices, the former of which has already been experimental confirmed. Here, a first-principles calculation is performed to investigate the struc- tural, magnetic, and electronic properties of Y half-substituted LaTiO3. Our results reveal that the magnetism of Yo.sLao.5TiO3 sensitively depends on its structural details because of the inher- ent phase competition. The lowest energy state is the ferromagnetic state, resulting in 0.25 μB/Ti. Furthermore, some configurations of Y0.500La0.5TiO3 exhibit hybrid improper polarizations, which can be significantly affected by magnetism, resulting in the multiferroic properties. Because of the quenching disorder of substitution, the real Y0.5La0.5TiO3 material with random A-site ions may exhibit interesting relaxor behaviors.
基金Acknowledgements The work was supported by the National Natural Science Foundation of China （Grant Nos. 51322206 and 11274060） and the Natural Science Foundation of Jiangsu Province of China （Grant No. BK20141329）.
文摘PbTiO3 is a simple but very important ferroelectric oxide that has been extensively studied and widely used in various technological applications. However, most previous studies and applications were based on the bulk material or the conventional [001]-orientated films. There are few studies on PbTiO3 films grown along other crystalline axes. In this study, a first-principles calculation was performed to compute the polarization of PbTiO3 films strained by SrTiO3 and LaAlO3 substrates. Our results show that the polarization of PbTiO3 films strongly depends on the growth orientation as well as the monoclinic angles. Further, it is suggested that the ferroelectricity of PbTiO3 mainly depends on the tetragonality of the lattice, instead of the simple strain.
