Factorization and Criticality in Finite X X Z Systems of Arbitrary Spin

CEREZO, M.; ROSSIGNOLI, R.; CANOSA, N.; RÍOS, E.

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Lugar: New York; Año: 2017 vol. 119 p. 2206051 - 2206056

0031-9007

We analyze ground state (GS) factorization in general arrays of spins $s_i$ with $XXZ$ couplings immersed in nonuniform fields. It is shown that an exceptionally degenerate set of completely separable symmetry-breaking GS´s can arise for a wide range of field configurations, at a quantum critical point where all GS magnetization plateaus merge. Such configurations include alternating fields as well as zero bulk field solutions with edge fields only and intermediate solutions with zero field at specific sites, valid for $d$-dimensional arrays. The definite magnetization projected GS´s at factorization can be analyticallydetermined and depend only on the exchange anisotropies, exhibiting critical entanglement properties. We also show that some factorization compatible field configurations may result in field-induced frustration and nontrivial behavior at strong fields.