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Interaction between impurities and solitons in quasi one-dimensional spin-Peierls systems

D. Augier·P. Hansen·D. Poilblanc·J. Riera·E. Sorensen
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Abstract

The role of the spin-phonon coupling in spin-Peierls chains doped with spin-0 or spin-1 impurities is investigated by various numerical methods such as exact diagonalization, quantum Monte Carlo simulations and Density Matrix Renormalization Group. Various treatments of the lattice, in a fully quantum mechanical way, classically in the adiabatic approximation or using a fixed three-dimensional dimerization pattern are compared. For an isolated chain, strong bonds form between the two spin-1/2 sites next to the impurity site, leading to the appearance of magneto-elastic solitons. We also show that these excitations do not bind to spin-0 impurities but are weakly attracted by spin-1 impurities. However, the interchain elastic coupling generates an effective confining potential at the non-magnetic impurity site which can lead to the formation of soliton-impurity bound states. We also predict that a soliton and an antisoliton bound to two impurities on the same chain can annihilate each other when the separation between the impurities is smaller than a critical value depending on the interchain elastic constant.

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D. Augier, P. Hansen, D. Poilblanc, J. Riera, E. Sorensen. 1998-07-18. Interaction between impurities and solitons in quasi one-dimensional spin-Peierls systems. https://arxiv.org/abs/cond-mat/9807265

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