Related papers: A Potts model for the distortion transition in LaM…
We investigate the Jahn-Teller structural phase transition in LaMnO$_3$ at $T_{JT} \simeq 750$ K using molecular dynamics simulations based on machine-learning force fields trained on ab initio data. Analysis of the site-site correlation…
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…
Jahn--Teller (JT) distortions are a key driver of physical properties in many correlated oxide materials. Cooperative JT distortions, in which long-range orbital order reduces the symmetry of the average structure macroscopically, are…
We present a revised atomistic picture of the order-disorder transition in the archetypal orbital-ordered perovskite material, LaMnO$_{3}$. Our study uses machine-learning-driven molecular-dynamics simulations which describe the temperature…
A study is made of an anisotropic Potts model in three dimensions where the coupling depends on both the Potts state on each site but also the direction of the bond between them using both analytical and numerical methods. The phase diagram…
We report on high-temperature electron spin resonance studies of a detwinned LaMnO$_3$ single crystal across the Jahn-Teller transition at $T_{\rm JT}$ = 750 K. The anisotropy of the linewidth and g-factor reflects the local Jahn-Teller…
LaMnO$_3$ is considered as a prototypical Jahn-Teller perovskite compound, exhibiting a metal to insulator transition at $T_{JT} = 750K$ related to the joint appearance of an electronic orbital ordering and a large lattice Jahn-Teller…
We analyze a three-state Potts model built over a lattice ring, with coupling $J_0$, and the fully connected graph, with coupling $J$. This model is effectively mean-field and can be exactly solved by using transfer-matrix method and…
The functional properties of transition metal perovskite oxides are known to result from a complex interplay of magnetism, polarization, strain, and stoichiometry. Here, we show that for materials with a cooperative Jahn-Teller distortion,…
We have studied the volume collapse of LaMnO$_3$ at the Jahn- Teller (JT) transition temperature T$_{JT}$=750 K which has recently been found in high temperature powder x- ray and neutron diffraction experiments. We construct a model…
We use the temperature of the structural phase transition to determine the Jahn-Teller (JT) coupling constant in the model derived for LaMnO$_3$ which includes both the superexchange between S=2 spins and the JT effect. We also investigate…
We have investigated the volume collapse occurring in LaMnO3 unit cell using the anisotropic Potts model modified by two types of anisotropic interactions which has been used to study the change of Mn-O bonds lengths as function of…
The three-state Potts model is numerically investigated on three-dimensional simple cubic lattices of up to \(128^3\) volume, concentrating on the neighborhood of the first-order phase transition separating the ordered and disordered…
A classical model for the lattice distortions of $\lax$ is derived and, in a mean field approximation, solved. The model is based on previous work by Kanamori and involves localized Mn d-electrons (which induce tetragonal distortions of the…
We investigate in this paper the ground state and the nature of the transition from an orientational ordered phase at low temperature to the disordered state at high temperature in a molecular crystal. Our model is a Potts model which takes…
The antiferromagnetic three-state Potts model on the simple-cubic lattice is studied using Monte Carlo simulations. The ordering in a medium temperature range below the critical point is investigated in detail. Two different regimes have…
We present evidence that the insulator to metal transition in (La,Ca)MnO3 near x~0.2 is driven by the suppression of coherent Jahn-Teller distortions, originating from d type orbital ordering. The orbital ordered state is characterised by…
We study the q-state Potts model on the simple cubic lattice with ferromagnetic interactions in one lattice direction, and antiferromagnetic interactions in the two other directions. As the temperature T decreases, the system undergoes a…
To understand the orbital ordering of $LaMnO_3$ in the ground state, we study it in the A-type spin antiferromagnetic state. We calculate the two-dimensional response functions associated with the Jahn-Teller $Q_2$ and $Q_3$ distortions and…
We study phase transition behavior of the Heisenberg model on a distorted triangular lattice with competing interactions. The ground-state phase diagram indicates that underlying symmetry can be changed by tuning parameters. We focus on two…