Related papers: Structural Phase Transitions
The Landau theory of phase transitions has been re-examined under the framework of a modified mean field theory in ferroelectrics. By doing so, one can see that there are two atomic movements involved in the ferroelectric phase transition;…
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…
Since there is both strong electron-phonon coupling during a ferroelectric/FE transition and superconducting/SC transition, it has been an important topic to explore superconductivity from the FE instability. Sn$_2$P$_2$Se$_6$ arouses broad…
Experimental investigations of the phase transition in GeTe provide contradictory conclusions regarding the nature of the phase transition. Considering growing interest in technological applications of GeTe, settling these disputes is of…
We analyze a system of polar molecules in a one-dimensional optical lattice. By controlling the internal structure of the polar molecules with static electric and microwave fields, we demonstrate the appearance of a quantum phase transition…
We investigate phase transitions and critical behaviors of the Kerr-Sen black hole in four dimensions. Computing the involved thermodynamical quantities including the specific heat and using the Ehrenfest scheme, we show that such a black…
We use neutron scattering to study the spin and lattice structures of single crystal and powder samples of Na$_{1-\delta}$FeAs ($T_c = 23$ K). On cooling from room temperature, the system goes through a series of phase transitions: first…
Chirality in solids is attracting growing attention as a potential ferroic order, yet virtually no paradigmatic example of a soft-mode achiral-to-chiral phase transition has been firmly established to date. Here we identify ferroelectric…
We systematically investigate the structural, electronic and magnetic properties of Mn$_n$ clusters ($n =$ 2$-$20) within the {\it ab-initio} pseudopotential plane wave method using generalized gradient approximation for the…
We report on a cooperative phenomenon of ferromagnetism and unconventional superconductivity (SC) in UGe$_2$ through the measurements of $^{73}$Ge nuclear-quadrupole-resonance (NQR) under pressure ($P$). The NQR spectra evidenced phase…
The improper ferroelectricity in YMnO$_3$ and other related multiferroic hexagonal manganites are known to cause topologically protected ferroelectric domains that give rise to rich and diverse physical phenomena. The local structure and…
Hexagonal manganites are multiferroic materials with two highly-dissimilar phase transitions: a ferroelectric transition (from P63/mmc to P63cm) at a temperature higher than 1000 K and an antiferromagnetic transition at TN=65 - 130 K.…
Phase transitions are governed by both intrinsic and extrinsic heterogeneities, yet capturing their spatio-temporal dynamics remains a challenge. While ultrafast techniques track phase changes on femtosecond timescales, the spatial…
Strain-regulated ferroelectric (FE) materials have long attracted significant attention due to their diverse applications. While soft-phonon theory and the (pseudo) Jahn-Teller effect have achieved considerable success in providing…
We have studied the pressure effect on electronic structures and magnetic orders of ternary iron selenide K$_{0.8}$Fe$_{1.6}$Se$_2$ by the first-principles electronic structure calculations. At low pressure, the compound is in the blocked…
Motivated by the recent discovery of a continuous ferromagnetic quantum phase transition in CeRh$_6$Ge$_4$ and its distinction from other U-based heavy fermion metals such as UGe$_2$, we develop a unified explanation of their different…
We investigate the topological phase transitions in graphene under the modulation of circularly polarized light, by analyzing the changes of edge states and its topological structures. A full phase diagram, with up to ten different…
Interlayer sliding degrees of freedom often determine the physical properties of two-dimensional (2D) materials. In graphene, for instance, the metastable rhombohedral stacking arrangement hosts correlated and topological electronic phases,…
Recent research suggests that the supercritical state consists of liquidlike and gaslike states where particle dynamics and key system properties are qualitatively different. We report experimental evidence of the structural crossover in…
The quantum Hall system can be used to study many-body physics owing to its multiple internal electronic degrees of freedom and tunability. While quantum phase transitions have been studied intensively, research on the temperature-induced…