Exact and numerical results for the dimerized spin - orbital chain


We establish exact results for the one-dimensional spin-orbital model for special values of the four-spin interaction V and dimerization parameter δ. The first exact result is at δ = 1/2 and V = −2. Because we find a very small but finite gap in this dimerized chain, this can serve as a very strong test case for numerical and approximate analytical techniques. The second result is for the homogeneous chain with V = −4 and gives evidence that the system has a spontaneously dimerized ground state. Numerical results indicate that the interplay between dimerization and interaction could result in gapless phases in the regime 0 ≤ V < −2. PACS numbers: 05.50+q, 75.10.Jm March 2000 The renewed interest in spin-orbital models [1, 2] stems from the belief that they are relevant to explain unusual magnetic properties of a wide range of materials. Representative examples are quasi-one-dimensional TDAE-C60 material [3], the Na2Ti2SbO2 and NaV2O5 compounds [4, 5], and two-dimensional LINIO2 samples [6]. In this letter we study the dimerized spinorbital chain with Hamiltonian

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@inproceedings{Martins2000ExactAN, title={Exact and numerical results for the dimerized spin - orbital chain}, author={M{\'a}rcio Jos{\'e} Martins and Bart Nienhuis}, year={2000} }