Related papers: $E\otimes e$ Jahn-Teller Effect in $C_{70}^{3-}$ S…
Distortions of the oxygen sublattice couple to $e_g$ orbitals of Mn$^{3+}$ and drive a cooperative Jahn-Teller (orbital ordering) transition in LaMnO$_3$. A simple model for this transition is studied. Without further adjustment, the model…
The longitudinal ultrasonic sound velocity and attenuation, the resistivity, and lattice parameters were studied as a function of temperature from 30 K to 300 K in La1-xCaxMnO3 (0.5<x<0.9). For all the samples, a dramatic stiffening of the…
We introduce an effective model for $e_g$ electrons to describe three-dimensional perovskite (La$_{1-x}$Sr$_{x}$MnO$_3$ and La$_{1-x}$Ca$_{x}$MnO$_3$) manganites and study the magnetic and orbital order on $4\times 4\times 4$ cluster using…
Due to the ubiquitous presence of a Berry phase, in most cases of dynamical Jahn-Teller systems the symmetry of the vibronic ground state is the same as that of the original degenerate electronic state. As a single exception, the linear H x…
We discuss analytical approximations to the ground-state phase diagram and the elementary excitations of the cooperative Jahn-Teller model describing strongly correlated spin-boson system on a lattice in various quantum optical systems.…
The relative importance of electron-lattice (e-l) and electron-electron (e-e) interactions in ordering orbitals in LaMnO$_3$ is systematically examined within the LDA+$U$ approximation of density functional theory. A realistic effective…
A theoretical model is proposed for the (0,0,1) superlattice manganite system (LaMnO$_3$)$_n$(SrMnO$_3$)$_m$. The model includes the electron-electron, electron-phonon, and cooperative Jahn-Teller interactions. It is solved using a version…
The coupling between doubly degenerate electronic states and doubly degenerate vibrations is analysed for an octahedral system on the basis of the introduction of an anharmonic Morse potential for the vibronic part. The vibrations are…
Generally, in case of the collective Jahn-Teller effect, a high-symmetry structure of a matrix in which quantum systems with degenerate ground state are inserted becomes distorted. This usually smooth transition can become abrupt only if…
The $5d^1$ ordered double perovskites present an exotic playground for studying novel multi-polar physics due to large spin-orbit coupling. We present Re L3 edge resonant inelastic X-ray scattering (RIXS) results that reveal the presence of…
The surprising insulating and superconducting states of narrow-band graphene twisted bilayers have been mostly discussed so far in terms of strong electron correlation, with little or no attention to phonons and electron-phonon effects. We…
We investigate the localized-electron character of the Mott-insulating phase in A$_3$C$_{60}$ using a single-site multiorbital electron model coupled to anisotropic molecular vibrations (Jahn--Teller phonons). We apply the spherical-tensor…
We have analyzed different correlation functions in a realistic spin-orbital model for half-doped manganites. Using a finite-temperature diagonalization technique the CE phase was found in the charge-ordered phase in the case of small…
We discuss the ground state entanglement of the $E\otimes\epsilon$ Jahn-Teller model in the presence of a strong transverse magnetic field as a function of the vibronic coupling strength. A complete characterization is given of the…
There is considerable evidence for some form of charge ordering on the hole-doped stripes in the cuprates, mainly associated with the low-temperature tetragonal phase, but with some evidence for either charge density waves or a flux phase,…
We report the temperature dependent mid- and near-infrared spectra of K4C60, Rb4C60 and Cs4C60. The splitting of the vibrational and electronic transitions indicates a molecular symmetry change of C604- which brings the fulleride anion from…
Cathode materials undergo various phase transitions during the charge/discharge process, and the structural transitions significantly affect the battery performance. Although phonon properties can provide a direct clue for structural…
The vibrational modes of Jahn-Teller molecules are affected by a Berry phase that is associated with a conical intersection of the adiabatic potentials. We investigate theoretically how this Berry phase affects transport through a single $E…
We discuss a hopping model of electrons between idealized molecular sites with local orbital degeneracy and dynamical Jahn-Teller effect, for crystal field environments of sufficiently high symmetry. For the Mott-insulating case (one…
We investigate the stability of the charge exchange (CE) phase within a microscopic model which describes a single plane as in La$_{0.5}$Sr$_{1.5}$MnO$_4$. The model includes Coulomb interactions (on-site and intersite), the Jahn-Teller…