We studied frequency and temperature dependences of impedance, electric modulus, dielectric permittivity ${\mathrm{Bi}}_{2∕3}{\mathrm{Cu}}_{3}{\mathrm{Ti}}_{4}{\mathrm{O}}_{12}$ in the ranges ${10}^{\ensuremath{-}1}--{10}^{6}\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}$ $\ensuremath{-}150--200\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$, respectively. first observed two electrical responses impedance modulus formalisms. Then we detected a Debye-like relaxation...

The puzzling nature of magnetic and lattice phase transitions iron pnictides is investigated via a first-principles Wannier function analysis representative parent compound LaOFeAs. A rare ferro-orbital ordering found to give rise the recently observed highly anisotropic coupling, drive both transitions--without resorting widely employed frustration or nesting picture. revealed necessity additional orbital physics leads correlated electronic structure fundamentally distinct from that...

We report a combined experimental and theoretical investigation of the magnetic structure honeycomb lattice magnet Na$_2$IrO$_3$, strong candidate for realization gapless spin-liquid. Using resonant x-ray scattering at Ir L$_3$-edge, we find 3D long range antiferromagnetic order below T$_N$=13.3 K. From azimuthal dependence Bragg peak, ordered moment is determined to be predominantly along {\it a}-axis. Combining data with first principles calculations, propose that most likely spin novel...

Frequency and temperature dependences of dielectric permittivity electric modulus pure Ba-doped Bi2Ti4O11 were studied in the ranges 10−1–106 Hz −150–350 °C, respectively. We found that antiferroelectric phase transition decreases with Ba doping. In studies, we also observed relaxation peaks shift to higher increasing frequency. Furthermore, formalism, conducting uncovered above 150 °C addition peak. discussed mechanisms for conduction processes based on TiO6 octahedra distortion a...

The varying metallic antiferromagnetic correlations observed in iron-based superconductors are unified a model consisting of both itinerant electrons and localized spins. decisive factor is found to be the sensitive competition between superexchange antiferromagnetism orbital-degenerate double-exchange ferromagnetism. Our results reveal crucial role Hund's rule coupling for strongly correlated nature system suggest that closer kin manganites than cuprates terms their diverse magnetism...

We report the topological electronic structure and magnetic magnetotransport properties of a noncentrosymmetric compound GdAlSi. Magnetic susceptibility shows an antiferromagnetic transition at ${T}_{\mathrm{N}}=32$ K. In-plane isothermal magnetization exhibits unusual hysteresis behavior higher field, rather than near zero field. Moreover, is asymmetric under positive negative fields. First-principles calculations were performed on various configurations, revealing that state ground state,...

Photoemission studies show the presence of a high-energy anomaly in observed band dispersion for two families cuprate superconductors, ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ and ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Ba}}_{x}{\mathrm{CuO}}_{4}$. The anomaly, which occurs at binding energy approximately 340 meV, is found to be anisotropic relatively weakly doping dependent. Scattering from short range or nearest neighbor spin excitations...

We report magnetoresistive and structural measurements of superconducting FeSe0.5Te0.5 epitaxial thin films grown by pulsed laser deposition. Enhanced onset transition temperature (∼17 K) is observed in some these films. Structural analysis x-ray diffraction high resolution transmission electron microscopy reveal that generally have significantly shorter out-of-plane lattice constant c than the bulk value, suggesting changes a dominating impact on iron-based superconductors. Our data also...

The electronic structure of ${\mathrm{Sr}}_{3}{\mathrm{CuIrO}}_{6}$, a model system for the $5d$ Ir ion in an octahedral environment, is studied through combination resonant inelastic x-ray scattering and theoretical calculations. Resonant spectra at ${L}_{3}$ edge reveal ${t}_{2g}$ manifold that split into three levels, contrast to expectations strong spin-orbit-coupling limit. Effective Hamiltonian ab inito quantum chemistry calculations find strikingly large noncubic crystal field...

Abstract Fundamental electronic principles underlying all transition metal compounds are the symmetry and filling of d -electron orbitals influence this on structural configurations responses. Here we use a sensitive local technique, x-ray atomic pair distribution function analysis, to reveal presence fluctuating local-structural distortions at high temperature in one such compound, CuIr 2 S 4 . We show that hitherto overlooked symmetry-lowering is origin will modify energy-level spectrum...

The Ising model describes collective behaviors such as phase transitions and critical phenomena in various physical, biological, economical, social systems. It is well known that spontaneous transition at finite temperature does not exist the with short-range interactions one dimension. Yet, little about whether this forbidden can be approached arbitrarily closely---at fixed temperature. Here I use symmetry analysis of transfer matrix to reveal existence ultranarrow crossover (UNPC) class...

The relative importance of electron-lattice ($e\mathrm{\text{\ensuremath{-}}}l$) and electron-electron ($e\mathrm{\text{\ensuremath{-}}}e$) interactions in ordering orbitals ${\mathrm{LaMnO}}_{3}$ is systematically examined within the local-density $\mathrm{\text{approximation}}+\mathrm{\text{Hubbard}}U$ approximation density functional theory. A realistic effective Hamiltonian derived from novel Wannier state analysis electronic structure. Surprisingly, $e\mathrm{\text{\ensuremath{-}}}l$...

It is demonstrated that novel spin frustration can be induced in ferromagnets with nonuniform Land\'{e} $g$-factors. The frustrated state characterized by a mutual interplay of typical ferromagnetic (FM) and antiferromagnetic (AF) features, such as the zero-field susceptibility being FM-like at low temperatures but AF-like high temperatures. also found to contain an exotic zero-temperature `half fire, half ice' critical point which spins on one sublattice are fully disordered other ordered....

In a previous paper [Weiguo Yin, Phys. Rev. Res. 6, 013331 (2024)], the forbidden spontaneous phase transition in one-dimensional Ising model was found to be approachable arbitrarily closely decorated ladders by ultranarrow crossover (UNPC) at given finite temperature ${T}_{0}$ with width $2\ensuremath{\delta}T$ reduced exponentially, which resembles genuine first-order large latent heat. Here, I reveal that can approached fixed as well single-chain models presence of magnetic field, is...

Abstract Oxide-ion conducting materials are gaining considerable attention in various applications ranging from oxide fuel cells to oxygen permeation membranes. The ion migration mechanisms the basis for designing oxide-ion materials. Here, enlightened by proton diffusion hydrogen-bond networks, we report coordination polyhedra cooperative mechanism with similar Grotthuss process of tellurites. Bi 2 Te O 7 and 4 11 were selected due their abundance secondary bonds hydrogen show high ionic...

The site-decorated Ising model is introduced to advance the understanding and physical realization of recently discovered one-dimensional finite-temperature ultranarrow phase crossover in an external magnetic field, overcoming complexity traditional bond-decorated models from geometric consideration. Furthermore, for higher-dimensional presence while they remain unsolved, exact solution about a novel spin-reversal transition -- accessible by slight change temperature or even weak field limit...

LiFePO4 (LFP) cathodes primarily degrade due to Li+ depletion and Fe (III) phase formation, while preserving their crystal structure, rendering them ideal candidates for direct regeneration. In spent LFP, however,...

We investigate the physical effects of translational symmetry breaking in Fe-based high-temperature superconductors due to alternating anion positions. In representative parent compounds, including newly discovered Fe-vacancy-ordered ${\mathrm{K}}_{0.8}{\mathrm{Fe}}_{1.6}{\mathrm{Se}}_{2}$, an unusual change orbital character is found across one-Fe Brillouin zone upon unfolding first-principles band structure and Fermi surfaces, suggesting that covering a larger necessary experiments. Most...

We report a combined experimental and theoretical study of the unusual ferromagnetism in one-dimensional copper-iridium oxide Sr(3)CuIrO(6). Utilizing Ir L(3) edge resonant inelastic x-ray scattering, we reveal large gap magnetic excitation spectrum. find that it is caused by an exchange anisotropy generating mechanism, namely, strong ferromagnetic arising from antiferromagnetic superexchange, driven alternating weak spin-orbit coupling on 5d 3d Cu ions, respectively. From symmetry...

We present a systematic study of the dipole alignment in polyvinylidene fluoride (PVDF) films using first-principles total energy calculations. The ground state single layer film is with all dipoles lying parallel to plane. This can also be explained by dipole-dipole interaction model. induced mirror charges on conducting substrates or non-negligible dielectric response play an important role aligning polarization perpendicular film. From fitting ab initio calculations, we obtain effective...

Abstract Polaron transport, in which electron motion is strongly coupled to the underlying lattice deformation or phonons, crucial for understanding electrical and optical conductivities many solids. However, little known experimentally about dynamics of individual phonon modes during polaron motion. It remains elusive whether polarons have a key role materials with strong electronic correlations. Here we report use new experimental technique, ultrafast MeV-electron diffraction, quantify...

We use first-principles methods to demonstrate that, in ${\mathrm{ZrTe}}_{5}$, a layered van der Waals material like graphite, atomic displacements corresponding five of the six zone-center ${A}_{g}$ (symmetry-preserving) phonon modes can drive topological transition from strong weak insulator with Dirac semimetal state emerging at transition, giving rise topology surface multidimensional space formed by modes. This implies that ${\mathrm{ZrTe}}_{5}$ be realized many different settings...