Excitations and Dynamics of Spin-Orbital Chains

概要

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The low-energy excitations and dynamics of a spin-orbital chain are calculated within a variational framework based on dimer states, exact diagonalization and the dynamical Density Matrix Renormalization Group (DMRG). In its dimerized phase, the spin-orbital chain exhibits a rich interplay of solitonic and magnonic excitations. While a solitonic excitation is the lowest excitation in a narrow region around the exactly solvable dimer point, magnonic excitations govern the phase transitions to neighbouring phases. Numerical calculations confirm that the curvature of the magnonic excitations is exactly flat on the so-called dimer line, changing sign across the line. This statement is not true for the solitonic excitations, which determine the lower edge of the excitation spectrum in the vicinity of the dimer line. DMRG calculations suggest that low-lying solitonic excitations may be experimentally hard to observe, with most spectral weight in higher-lying magnons.
理論物理学刊行会の論文
2002-06-28