Phase diagram of the alternating-spin Heisenberg chain with extra isotropic three-body exchange interactions |
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Authors: | Nedko B. Ivanov Jörg Ummethum Jürgen Schnack |
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Affiliation: | 1. Department of Physics, Bielefeld University, P.O. Box 100131, 33501, Bielefeld, Germany 2. Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko chaussee 72, 1784, Sofia, Bulgaria
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Abstract: | For the time being isotropic three-body exchange interactions are scarcely explored and mostly used as a tool for constructing various exactly solvable one-dimensional models, although, generally speaking, such competing terms in generic Heisenberg spin systems can be expected to support specific quantum effects and phases. The Heisenberg chain constructed from alternating S = 1 and σ = 1/2 site spins defines a realistic prototype model admitting extra three-body exchange terms. Based on numerical density-matrix renormalization group (DMRG) and exact diagonalization (ED) calculations, we demonstrate that the additional isotropic three-body terms stabilize a variety of partially-polarized states as well as two specific non-magnetic states including a critical spin-liquid phase controlled by two Gaussinal conformal theories as well as a critical nematic-like phase characterized by dominant quadrupolar S-spin fluctuations. Most of the established effects are related to some specific features of the three-body interaction such as the promotion of local collinear spin configurations and the enhanced tendency towards nearest-neighbor clustering of the spins. It may be expected that most of the predicted effects of the isotropic three-body interaction persist in higher space dimensions. |
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