Related papers: Magnetodielectric effect and optic soft mode behav…
Spin and lattice dynamics of CaMn7O12 ceramics were investigated using infrared, THz and inelastic neutron scattering (INS) spectroscopies in the temperature range 2 to 590 K, and, at low temperatures, in applied magnetic fields of up to 12…
We have measured near normal incidence far infrared (FIR) reflectivity spectra of a single crystal of TbMnO3 from 10K to 300K in the spectral range of 50 cm$^{-1}$ to 700 cm$^{-1}$. Fifteen transverse optic (TO) and longitudinal optic (LO)…
We measured the temperature dependent infrared reflectivity spectra of MnF2 between 4 K and room temperature. We show that the phonon spectrum undergoes a strong renormalization at TN. The ab-initio calculation we performed on this compound…
At low temperatures, EuTiO$_3$ system has very large resistivities and exhibits colossal magnetoresistance. Based on a first principle calculation and the dynamical mean-field theory for small polaron we have calculated the transport…
Eu1-xYxMnO3 exhibits, unlike other magnetoelectric systems, very distinctive features. Its magnetoelectric properties is driven by the magnetic spin of the Mn3+ ion, but they can be drastically changed by varying the content of Y3+, which…
We investigated the infrared reflectivity of several Mg- and Si-substituted CuGeO3 single crystals. The temperature dependent b-axis and c-axis optical response is reported. For T<Tsp we detected the activation of zone-boundary phonons…
The structural phase transition in hexagonal BaMnO$_3$ occurring at $T_c$=130 K was studied in ceramic samples using electron and X-ray diffraction, second harmonic generation as well as by dielectric and lattice dynamic spectroscopies. The…
High-frequency dielectric studies of Bi_0.85Nd_0.15FeO_3 ceramics performed betweeen 100 and 900 K reveal hardening of most polar phonons on cooling below antiferroelectric phase transition, which occurs near 600 K. Moreover, a strong THz…
Understanding collective phenomena in quantum materials from first principles is a promising route toward engineering materials properties on demand and designing new functionalities. This work examines the quantum paraelectric state, an…
EuTiO_{3} undergoes a structural phase transition from cubic to tetragonal at T_S = 282 K which is not accompanied by any long range magnetic order. However, it is related to the oxygen ocathedra rotation driven by a zone boundary acoustic…
We have investigated the phonon and the magnetic excitations in LaCoO3 by inelastic neutron scattering measurements. The acoustic phonon dispersions show some characteristic features of the folded Brillouin zone (BZ) for the rhombohedrally…
We report on TmMnO3 far infrared emissivity and reflectivity spectra from 1910 K to 4 K. At the highest temperature the number of infrared bands is lower than that predicted for centrosymmetric P63/mmc (D6h4) (Z=2) space group due high…
The multiferroic properties of EuTiO3 are greatly enhanced when a sample is strained, signifying that coupling between strain and structural, magnetic or ferroelectric order parameters is extremely important. Here resonant ultrasound…
BaTiO3 is a model ferroelectric perovskite whose properties are highly sensitive to local structure, defect chemistry, and dopant distribution. However, conventional diffraction mainly probes the average lattice and can miss subtle changes…
Temperature dependent inelastic neutron-scattering measurements of the generalized phonon density-of-states for superconducting MgCNi_3, T_c=8 K, give evidence for a soft-mode behavior of low-frequency Ni phonon modes. Results are compared…
We report on far- and mid-infrared reflectivity of NdMnO3 from 4 K to 300K. Two main features are distinguished in the infrared spectra: active phonons in agreement with the expected for orthorhombic D2h 16-Pbnm (Z=4) space group remaining…
Time-resolved two color pump-probe polarization spectroscopy was performed at room temperature on SrTiO3 films grown directly on Si with film thickness varying from 2 nm to 7.8 nm. The E soft mode with a characteristic frequency of 0.2 THz…
Several SrTiO3 (STO) thin films without electrodes processed by pulsed laser deposition, of thicknesses down to 40 nm, were studied using infrared transmission and reflection spectroscopy. The complex dielectric responses of polar phonon…
We have investigated the magnetocaloric effect in single and polycrystalline samples of quantum paraelectric EuTiO3 by magnetization and heat capacity measurements. Single crystalline EuTiO3 shows antiferromagnetic ordering due to Eu2+…
A comparative analysis of the structural phase transitions of EuTiO3 and SrTiO3 (at TS = 282 and 105 K, respectively) is made on the basis of phonon-dispersion and density functional calculations. The phase transition of EuTiO3 is predicted…