相关论文: Anharmonic stabilization of ferrielectricity in Cu…
The appearance of spontaneous polarization in CuInP$_{2}$S$_{6}$ ferrielectrics is related to the second order Jahn-Teller effect for copper cations located in a double-well local potential, the stereoactivity of indium cations located in a…
We have revisited the Kittel model that describes antiferroelectricity (AFE) in terms of two sublattices of spontaneous polarization with antiparallel couplings. By constructing the comprehensive phase diagram including the…
We consider nanoflakes of van der Waals ferrielectric CuInP$_2$S$_6$ covered by an ionic surface charge and reveal the appearance of polar states with relatively high polarization ~5 microC/cm$^2$ and stored free charge ~10 microC/cm$%2$,…
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 present a thorough analysis of the foundations of models of stabilization of negative capacitance (NC) in a ferroelectric (FE) layer by capacitance matching to a dielectric layer, which claim that the FE is stabilized in a low…
Ferroelectrics that are also ionic conductors offer possibilities for novel applications with high tunability, especially if the same atomic species causes both phenomena. In particular, at temperatures just below the Curie temperature,…
The vibrational properties of ErTe$_3$ were investigated using Raman spectroscopy and analyzed on the basis of peculiarities of the RTe$_3$ crystal structure. Four Raman active modes for the undistorted structure, predicted by factor-group…
Understanding how optical excitation couples with polarization and interfacial electrostatics in van der Waals (vdW) ferroelectrics (FEs) is essential for the development of light-programmable nanoelectronic and optoelectronic devices.…
In order to explore the properties of a two-sublattice ferroelectric, we measured the infrared and Raman scattering response of CuInP2S6 across the ferroelectric and glassy transitions and compared our findings to a symmetry analysis,…
2D ferroelectric (FE) materials have opened new opportunities in non-volatile memories, computation and non-linear optics due to their robust polarization in the ultra-thin limit and inherent flexibility in device integration. Recently,…
We identify a first-order, isosymmetric transition between a ferrielectric (FiE) and ferroelectric (FE) state in $A$-site ordered LaScO$_{3}$/BiScO$_{3}$ and LaInO$_{3}$/BiInO$_{3}$ superlattices. Such a previously unreported ferroic…
Polarized Raman-scattering spectra of superconducting, single-crystalline FeSe evidence pronounced phonon anomalies with temperature reduction. A large 6.5% hardening of the B_1g(Fe) phonon mode is attributed to the suppression of local…
We study from first-principles calculations the ferroelectric structural phase transition of Pb$_5$Ge$_3$O$_{11}$ crystal. The calculations of phonons and Born effective charges of the paraelectric phase allow us to identify a polar…
Amongst the X(Sn,Pb)Y$_3$ perovskites currently under scrutiny for their photovoltaic applications, the cubic B-$\alpha$ phase of CsSnI$_3$ is arguably the best characterized experimentally. Yet, according to the standard harmonic theory of…
Heterostructures of topological insulators and ferromagnets offer new opportunities in spintronics and a route to novel anomalous Hall states. In one such structure, EuS/Bi$_{2}$Se$_{3}$ a dramatic enhancement of the Curie temperature was…
Coherent ferrons, the quanta of polarization waves, can potentially be hybridized with many other quasiparticles for achieving novel control modalities in quantum communication, computing, and sensing. Here, we theoretically demonstrate a…
An emerging area in condensed matter physics is the use of multilayered heterostructures to enhance ferroelectricity in complex oxides. Here, we demonstrate that optically pumping carriers across the interface between thin films of a…
Polarized Raman scattering spectra of superconducting K$_x$Fe$_{2-y}$Se$_2$ and nonsuperconducting K$_{0.8}$Fe$_{1.8}$Co$_{0.2}$Se$_2$ single crystals were measured in a temperature range from 10 K up to 300 K. Two Raman active modes from…
In this work, we performed temperature-dependent Raman spectroscopy studies on three layered metal thiophosphates: CuInP2S6, CuCrP2S6, and CuInP2S6-In4/3P2S6 heterostructures. These materials are emerging multiferroics, with CuInP2S6 and…
We used Raman light scattering to study the current-stabilized nonequilibrium semimetallic and metallic phases in Ca$_2$RuO$_4$. By determining the local temperature through careful analysis of the Stokes and anti-Stokes intensities, we…