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The interaction of coexisting structural instabilities in multiferroic materials gives rise to intriguing coupling phenomena and extraordinarily rich phase diagrams, both in bulk materials and strained thin films. Here we investigate the…
We report the thermoelectric properties of polycrystalline samples of Ca3Pb1-xBixO (x = 0, 0.1, 0.2) and Ca3SnO, both crystallizing in a cubic antiperovskite-type structure. The Ca3SnO sample shows metallic resistivity and its…
AgNbO$_3$ is a lead-free perovskite with considerable potential for energy storage and optoelectronic applications, yet its low-temperature crystal structure has remained controversial. In this Letter, we revisit its low-energy structural…
A dielectric nonlinear response in model two-phase composites, prepared from a displacive ferroelectric material with a dominant dielectric response due to a single oscillator ferroelectric mode and a dielectric material, is characterized…
Since conduction electrons of a metal screen effectively the local electric dipole moments, it was widely believed that the ferroelectric-like distortion cannot occur in metals. Recently, metallic LiOsO3, was discovered to be the first…
Reflection and transmission as a function of temperature have been measured on a single crystal of the magnetoelectric ferrimagnetic compound Cu$_{2}$OSeO$_{3}$ utilizing light spanning the far infrared to the visible portions of the…
Using density-functional theory with ultrasoft pseudopotentials, we previously investigated the structural and electronic properties of the low-pressure (cubic, tetragonal, and monoclinic) phases of ZrO2 and HfO2, in order to elucidate…
We present an ab initio approach for the calculation of phonon self-energies and their fluctuation diagnostics, which allows us to identify the electronic processes behind phonon anomalies. Application to the transition-metal-dichalcogenide…
We report the Pockels electro-optic properties of ZrO2 and HfO2 orthorhombic Pbc21 and rhombohedral R3m ferroelectric phases, and we compare them to the well-known LiNbO3 Pockels material from density functional theory calculations using…
Using density functional theory we investigate the lattice instability and electronic structure of recently discovered ferroelectric metal LiOsO$_3$. We show that the ferroelectric-like lattice instability is related to the Li-O distortion…
For Sn$_2$P$_2$S$_6$ ferroelectrics, the appearance of spontaneous polarization is related to stereoactivity of tin cations and valence fluctuations of phosphorous cations. Here, the continuous phase transition and its behavior under…
We explore the effect of charge carrier doping on ferroelectricity using density functional calculations and phenomenological modeling. By considering a prototypical ferroelectric material, BaTiO3, we demonstrate that ferroelectric…
We present a first-principles study of the relationship between stress, temperature and electronic properties in piezoelectric ZnO. Our method is a plane wave pseudopotential implementation of density functional theory and density…
The reflectivity of single-crystalline CoO has been studied by optical spectroscopy for wave numbers ranging from 100 to 28,000\wn and for temperatures 8 $< T <$ 325 K\@. A splitting of the cubic IR-active phonon mode on passing the…
It is shown that the thermodynamic potential of the domain-like incommensurate (IC) phase of the K_2SeO_4 crystal should be supplemented with a term, taking into account the local, Lorentz electric field. The latter qualitatively changes…
YMnO3 thin films were grown on n - type Si substrate by nebulized spray pyrolysis in Metal - Ferroelectric - Semiconductor (MFS) configuration. The C-V characteristics of the film in MFS structure exhibit hysteretic behavior consistent with…
Hyperferroelectrics are receiving a growing interest thanks to their unique property to retain a spontaneous polarization even in presence of a depolarizing field. Nevertheless, general microscopic mechanisms driving hyperferroelectricity,…
Ferroelectricity has been found to occur in several insulating systems, such as TbMnO$_3$ (TMO) and Ni$_3$V$_2$O$_8$ (NVO) which have more than one phase with incommensurately modulated long-range magnetic order. Here we give a…
We have investigated crystal field and phonon dynamics of the multiferroic orthoferrite DyFeO$_3$ via polarized infrared spectroscopy. Reflectance of single crystals was measured in the far- to mid-infrared spectral range at range of…
We report the first principles investigations on the phonons of three polytypes of BaTiO3 (BTO): paraelectric (PE) cubic Pm-3m and two ferroelectric (FE) phases, tetragonal P4mm and rhombohedral R3m. The phonon frequencies calculated using…