Spin-1 chain doped with mobile S=1/2 fermions

Abstract

We investigate doping of a two-orbital chain with mobile $S=1/2$ fermions as a valid model for ${\mathrm{Y}}_{2-\mathrm{x}}\mathrm{C}{\mathrm{a}}_{\mathrm{x}}\mathrm{BaNi}{\mathrm{O}}_5$. The S=1 spins are stabilized by strong, ferromagnetic (fm) Hund's rule couplings. We calculate correlation functions and thermodynamic quantities by DMRG methods and find a new hierarchy of energy scales in the spin sector upon doping. Gapless spin-excitations are generated at a lower energy scale by interactions among itinerant polarons created by each hole and coexist with the larger scale of the gapful spin-liquid background of the S=1 chain accompanied by a finite string-order parameter.

5 pages and 5 eps-figures

Cited by in corpus (7)

• The density-matrix renormalization group
• Application of the density matrix renormalization group method to finite temperatures and two-dimensional systems
• Correlations, spin dynamics, defects: the highly-frustrated Kagomé bilayer
• Random interactions and spin-glass thermodynamic transition in the hole-doped Haldane system Y${}_{2-x}$Ca${}_x$BaNiO${}_5$
• Origin of Spin Incommensurability in Hole-doped S=1 ${\mathrm{Y}}_{2-\mathrm{x}}\mathrm{C}{\mathrm{a}}_{\mathrm{x}}\mathrm{BaNi}{\mathrm{O}}_5$ Chains
• Instability of the Haldane Phase: Roles of Charge Fluctuations and Hund's Coupling
• Incommensurate structure factor in a hole-doped spin-1 system