Year: 2015
Type: article
Abstract: We determine the conditions for the existence of nontransverse factorizing magnetic fields in general spin arrays with anisotropic $XYZ$ couplings of arbitrary range. It is first shown that a uniform, maximally aligned, completely separable eigenstate can exist just for fields ${\mathbit{h}}_{s}$ parallel to a principal plane and forming four straight lines in the field space, with the alignment direction different from that of ${\mathbit{h}}_{s}$ and determined by the anisotropy. Such a state always becomes a nondegenerate ground state for sufficiently strong (yet finite) fields along these lines, in both ferromagnetic and antiferromagnetic-type systems. In antiferromagnetic chains, this field coexists with the nontransverse factorizing field ${\mathbit{h}}_{s}^{\ensuremath{'}}$ associated with a degenerate N\'eel-type separable ground state, which is shown to arise at a level crossing in a finite chain. It is also demonstrated for arbitrary spin that pairwise entanglement reaches full range in the vicinity of both ${\mathbit{h}}_{s}$ and ${\mathbit{h}}_{s}^{\ensuremath{'}}$, vanishing at ${\mathbit{h}}_{s}$ but approaching small yet finite side limits at ${\mathbit{h}}_{s}^{\ensuremath{'}}$, which are analytically determined. The behavior of the block entropy and entanglement spectrum in their vicinity is also analyzed.
Source: Physical Review B
Authors: M. Cerezo, R. Rossignoli, N. Canosa
Language: English
Topic: Quantum many-body systems
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2491702678