Magnetic excitations in one-dimensional spin-orbital models

Abstract

We study the dynamics and thermodynamics of one-dimensional spin-orbital models relevant for transition metal oxides. We show that collective spin, orbital, and combined spin-orbital excitations with infinite lifetime can exist, if the ground state of both sectors is ferromagnetic. Our main focus is the case of effectively ferromagnetic (antiferromagnetic) exchange for the spin (orbital) sector, respectively, and we investigate the renormalization of spin excitations via spin-orbital fluctuations using a boson-fermion representation. We contrast a mean-field decoupling approach with results obtained by treating the spin-orbital coupling perturbatively. Within the latter self-consistent approach we find a significant increase of the linewidth and additional structures in the dynamical spin structure factor as well as Kohn anomalies in the spin-wave dispersion caused by the scattering of spin excitations from orbital fluctuations. Finally, we analyze the specific heat c(T) by comparing a numerical solution of the model obtained by the density-matrix renormalization group with perturbative results. At low temperatures T we find numerically c(T) T pointing to a low-energy effective theory with dynamical critical exponent z=1.

18 pages, 16 figures

References in corpus (10)

• Mixtures of Bosonic and Fermionic Atoms in Optical Lattices
• Instabilities in binary mixtures of one-dimensional quantum degenerate gases
• Spin-Orbital Entanglement and Violation of the Goodenough-Kanamori Rules
• Evolution of Spin-Orbital-Lattice Coupling in the $R$VO${}_3$ Perovskites
• Theory of optical spectral weights in Mott insulators with orbital degrees of freedom
• Thermally activated Peierls dimerization in ferromagnetic spin chains
• Temperature driven crossover phenomena in the correlation lengths of the one-dimensional t-J model
• Entropy Driven Dimerization in a One-Dimensional Spin-Orbital Model
• Spin-Orbital Entanglement and Phase Diagram of Spin-orbital Chain with $SU(2)\times SU(2)$ Symmetry
• Thermodynamics of a one-dimensional S=1/2 spin-orbital model

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• Exotic spin orders driven by orbital fluctuations in the Kugel-Khomskii model
• Quantum phase transitions in exactly solvable one-dimensional compass models
• Topological Order in an Entangled SU(2)$\otimes$XY Spin-Orbital Ring
• Defect states and excitations in a Mott insulator with orbital degrees of freedom: Mott-Hubbard gap versus optical and transport gaps in doped systems
• The dimerized ferromagnetic Heisenberg chain
• Quantum entanglement in the one-dimensional spin-orbital SU(2)$\otimes XXZ$ model
• Entanglement Driven Phase Transitions in Spin-Orbital Models
• Locally tunable disorder and entanglement in the one-dimensional plaquette orbital model
• Spectral properties of spin-orbital polarons as a fingerprint of orbital order
• Long-range spin-orbital order in the spin-orbital SU(2)$\times$SU(2)$\times$U(1) model
• Exotic Spin Order due to Orbital Fluctuations