Related papers: Fluctuations, Higher Order Anharmonicities, and La…
Variations with oxygen concentration of titanium lattice parameters are obtained by means of ab initio calculations, considering the impact of oxygen ordering. The quasiharmonic approximation is used to take into account the thermal…
We consider Aharonov - Bohm effect at normal metal-inhomogeneous LOFF superconducting state transition. It is shown that magnetic flux can increase the transition temperature and AB oscillations can have the double-peak structure at one…
A wide range of quasi-one-dimensional materials, consisting of weakly coupled chains, undergo three-dimensional phase transitions that can be described by a complex order parameter. A Ginzburg-Landau theory is derived for such a transition.…
Spinor Bose-Einstein condensates provide a unique example in which the Bogoliubov theory fails to describe the metastability associated with first-order quantum phase transitions. This problem is resolved by developing the spinor Beliaev…
At temperatures well below the Fermi temperature $T_F$, the coupling of magnetic fluctuations to particle-hole excitations in a two-component Fermi gas makes the transition to itinerant ferromagnetism a first order phase transition. This…
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…
An effective Hamiltonian for the ferroelectric transition in $PbTiO_3$ is constructed from first-principles density-functional-theory total-energy and linear-response calculations through the use of a localized, symmetrized basis set of…
The barium sodium niobate (BNN) with tungsten-bronze structure is one of well-known optical crystals for electro-optic and nonlinear optic applications. This paper reviews the ferroelectric instability of BNN crystals. BNN is a uniaxial…
Nematic phase transitions in high-temperature superconductors have a strong impact on the electronic properties of these systems. BaFe$_2$As$_2$,\@ with an established nematic transition around 137 K induced by magnetic fluctuations, and…
The free energy of barium titanate is computed around the Curie temperature as a function of polarization from the first-principles derived effective hamiltonian of Zhong, Vanderbilt and Rabe [Phys. Rev. Lett. 73, 1861 (1994)], through…
This study shows that the charge disproportionation at the Bi site in BaBiO$_3$ alters as a function of temperature. Decreasing the temperature from 300K down to 160K leads to a significant modification of the density of states…
The Verwey phase transition in magnetite is analyzed on the basis of the Landau theory. The free energy functional is expanded in a series of components belonging to the primary and secondary order parameters. A low-temperature phase with…
Properties of (BaTiO$_3$)$_1$/(BaZrO$_3$)$_n$ ferroelectric superlattices (SLs) with $n = {}$1--7 grown in the [001] direction are calculated from first principles within the density functional theory. It is revealed that the…
Analytical expressions for the magnetoelastic anisotropy constants of cubic magnetic systems are derived for rectangular and oblique distortions originating from epitaxial growth on substrates with lower crystal symmetry. In particular, the…
Using high statistics datasets generated in (2+1)-flavor QCD calculations at finite temperature we present results for low order cumulants of net baryon-number fluctuations at non-zero values of the baryon chemical potential. We calculate…
Polar nematic liquid crystals are new classes of condensed-matter states where the inversion symmetry common to the traditional apolar nematics is broken. Establishing theoretical descriptions for the novel phase states is an urgent task.…
We consider the presence of cosmic string induced density fluctuations in the universe at temperatures below the electroweak phase transition temperature. Resulting temperature fluctuations can restore the electroweak symmetry locally,…
Structural, magnetic, electrical transport, and heat capacity data are reported for single crystals of TlFe1.6Se2. This compound crystallizes in a tetragonal structure similar to the ThCr2Si2 structure, but with vacancies in the Fe layer.…
We have investigated the out-of-plane lattice relaxation related to the ferroelectric transitions in epitaxial BaTiO$_3$ (BTO) films using synchrotron X-ray diffraction. Under either compressive strain or tensile strain, there is evidence…
Phase transition in U(n)xU(n) models is investigated for arbitrary flavor number n. We present a nonperturbative, 3+1 dimensional finite temperature treatment of obtaining the effective potential, based on a chiral invariant expansion of…