Related papers: Lattice Dynamics in a strongly dimerized low-dimen…
We investigate the spin dynamics of excitons interacting with acoustic phonons in quantum wells, quantum wires and quantum disks by employing a multiband model based on the $4\times4$ Luttinger Hamiltonian. We also use the Bir-Pikus…
We investigate the interplay between lattice symmetry, phonons, and magnetism in the quasi-one-dimensional ladder compound BaFe$_2$S$_3$ by combining polarized synchrotron infrared spectroscopy, hybrid-functional density functional theory…
The role of the orbital degrees of freedom is studied theoretically for the spin dynamics of $R_{1-x}A_x$MnO$_3$. Based on the meanfield solution, an RPA calculation has been done and it is found that the $d_{x^2-y^2}$-type orbital is…
We study electron propagation in a molecular lattice model. Each molecular site involves doubly degenerate electronic states coupled to doubly degenerate molecular vibration, leading to a so--called E-e type of Jahn-Teller Hamiltonian. For…
The orbital excitations of a series of transition-metal compounds are studied by means of optical spectroscopy. Our aim was to identify signatures of collective orbital excitations by comparison with experimental and theoretical results for…
With polarized and angle-resolved Raman spectroscopy studies on single two-dimensional layered perovskites (2DLP) flakes with different ammonium molecules as organic cations, in 2020 we revealed the very rich phonon spectra in the…
We study the renormalization of magnons by charge and coupled orbital-lattice fluctuations in colossal magnetoresistance compounds. The model considered is an orbitally degenerate double-exchange system coupled to Jahn-Teller active…
Several spin systems with low dimensionality develop a spin-dimer phase within a molecular orbital below TS, competing with long-range antiferromagnetic order. Very often, preferential orbital occupancy and ordering are the actual driving…
We report a comprehensive investigation of the lattice dynamics of URu$_2$Si$_2$ as a function of temperature using Raman scattering, optical conductivity and inelastic neutron scattering measurements as well as theoretical {\it ab initio}…
We study the spin-1/2 Heisenberg model in a lattice that interpolates between the triangular and the kagome lattices. The exchange interaction along the bonds of the kagome lattice is J, and the one along the bonds connecting kagome and…
We present a study of the magnetic order and the structural stability of two-dimensional quantum spin systems in the presence of spin-lattice coupling. For a square lattice it is shown that the plaquette formation is the most favourable…
Coupling between spin and lattice degrees of freedom are important in geometrically frustrated magnets where they can lead to degeneracy lifting and novel orders. We show that moderate spin-lattice couplings in triangular and Kagome…
Reproducing the electronic structure of AM$_4$X$_8$ lacunar spinels with a breathing pyrochlore lattice is a great theoretical challenge due to the interplay of various factors. The character of the M$_4$X$_4$ cluster orbitals is critically…
The density matrix renormalization group method is used to investigate the spin-Peierls transition for Heisenberg spins coupled to quantized phonons. We use a phonon spectrum that interpolates between a gapped, dispersionless (Einstein)…
This paper reviews recent experimental and theoretical developments of the dynamic Jahn-Teller effect-driven phenomena in heavy transition metal-based spin-orbit Mott insulators. In cubic $4d/5d$ transition metal compounds, the spin,…
Orbital degrees of freedom play an important role for understanding the emergence of unconventional quantum phases. Ultracold atomic gases in optical lattices provide a wonderful platform to simulate orbital physics. In this work, we…
Motivated by the experiments on the organic compound $(Per)_{2}[Pt(mnt)_{2}]$, we study the ground state of the one-dimensional Kondo lattice model at quarter filling with the density matrix renormalization group method. We show a coupled…
Understanding spin and lattice excitations in a metallic magnetic ordered system form the basis to unveil the magnetic and lattice exchange couplings and their interactions with itinerant electrons. Kagome lattice antiferromagnet FeGe is…
We analyze the interaction of lattice vibrations (phonon wave-packets) with an asymmetric kink soliton initially at rest. We employ the $\phi^6$ model in one space and one time dimensions for various lattice spacings and consider two…
We study an extended model to describe the spin-lattice coupling, incorporating individual vibrations of bonds and atomic sites alongside distance-dependent exchange interactions. The proposed spin Hamiltonian can be effectively considered…