Influence of the cooperative Jahn-Teller effect on the transport-and magnetic properties of La 7/8 Sr 1/8 MnO 3 single crystals Abstract The low-doped magnetic perovskite La 7/8 Sr 1/8 MnO 3 undergoes within the paramagnetic-semiconducting phase a first-order structural transition due to antiferrodistorsive ordering of Jahn-Teller deformed MnO 6 octahedra. This allows to study not only the infl...

The possible role of the van Hove singularity (vHs) in stabilizing the low-temperature orthorhombic (LTO) phase transition in La 2−x Sr x CuO 4 (LSCO) is discussed. It is found that the vHs can drive a structural distortion in two different ways, either due to spin-orbit coupling or to dynamic Jahn-Teller (JT) effects. This paper discusses the latter effect in some detail. It is shown that a mo...

We present an extensive study of interfaces defined in the Z4 spin lattice representation of the Ashkin-Teller (AT) model. In particular, we numerically compute the fractal dimensions of boundary and bulk interfaces at the Fateev-Zamolodchikov point. This point is a special point on the self-dual critical line of the AT model and it is described in the continuum limit by the Z4 parafermionic th...

In the present paper we report on an analysis of the fine structure of the first excited quartet T2g of Mn4+ ions which occupy the octahedral site in the Cs2GeF6 host crystal. The dynamic T2g⊗ (eg + t2g) Jahn–Teller effect is considered in details, including the Ham effect of the reduction of the spin-orbit splitting and displacements of the ligands due to the combined effect of the a1g and eg ...

Density Functional Theory (DFT) in conjuction with the Intrinsic Distortion Path (IDP) is employed to study the Jahn-Teller (JT) effect in all four diastereoisomers of tris(ethylenediamine)copper(II) ([Cu(en)3] ) and tris(ethyleneglycol)copper(II) ([Cu(eg)3] ) complexes. As a consequence of the JT effect all the isomers tetragonally elongate to the C2 configurations. Although there are energy d...

The topology of the ground-state potential energy surface of M(CN)(6) with orbitally degenerate (2)T(2g) (M = Ti(III) (t(2g)(1)), Fe(III) and Mn(II) (both low-spin t(2g)(5))) and (3)T(1g) ground states (M = V(III) (t(2g)(2)), Mn(III) and Cr(II) (both low-spin t(2g)(4))) has been studied with linear and quadratic Jahn-Teller coupling models in the five-dimensional space of the epsilon(g) and tau...

Understanding the relationship between the superconducting, the neighboring insulating, and the normal metallic state above T c is a major challenge for all unconventional superconductors. The molecular A3C60 fulleride superconductors have a parent antiferromagnetic insulator in common with the atom-based cuprates, but here, the C60 (3-) electronic structure controls the geometry and spin state...

In a two orbital double exchange model we formulate Jahn-Teller coupled charge density wave in half-filled limit. Softening of Jahn-Teller phonons corresponding to distortion modes Q2 or Q3 associated with perfect nesting of Fermi surface leads to this instability at low temperature. The gap equation for charge density wave state and its dependences on electron-lattice coupling are calculated e...

We analyze the supersymmetry and the shape invariance of the potentials of the (1+1) relativistic oscillators we have recently proposed [1, 2]. In the general relativity, the geometric models play the role of kinematics, helping us to understand the characteristics of the classical or quantum free motion on a given background. One of the simplest (1+1) geometric models is that of the quantum re...

Hydroxyapatite (HAp) supported Nickel (Ni) catalyst was prepared using wet impregnation method. A series of Ni/HAp catalysts have been prepared by varying the amount of nickel viz., 3, 6 and 12 %. The highest Brunauer-Emmett-Teller (BET) surface area of 92.18 m/g was noticed for a catalyst composition containing 3% nickel loading. The scanning electron microscopy (SEM) studies revealed a smooth...