Spin correlation functions and susceptibilities in the easy-plane XXZ chain

Abstract

We present a Green's-function theory of magnetic short-range order in the $S=1/2$ easy-plane XXZ chain based on the projection method for the dynamic spin susceptibility and a decoupling of three-spin operator products introducing vertex parameters. The longitudinal and transverse static susceptibilities and two-point correlation functions of arbitrary range are calculated self-consistently for all wavenumbers, temperatures, and anisotropy parameters $-1\le \Delta \le 1$. In the easy-plane ferromagnetic region $(\Delta <0)$, the longitudinal correlators of spins at distance $n$ change sign at a finite temperature $T_0(n,\Delta )$, in reasonable agreement with recent data obtained by finite-chain diagonalizations. The temperature dependence of the uniform static susceptibilities exhibits a maximum which is explained as an effect of magnetic short-range order which decreases with increasing temperature.

5 pages, 6 figures, submitted to Phys. Rev. B

References in corpus (3)

• Magnetic Order-Disorder Transition in the Two-Dimensional Spatially Anisotropic Heisenberg Model at Zero Temperature
• Quantum-classical crossover in the spin 1/2 XXZ chain
• Temperature dependent spatial oscillations in the correlations of the XXZ spin chain

Cited by in corpus (4)

• The Kernel Polynomial Method
• Green's-function theory of the Heisenberg ferromagnet in a magnetic field
• Magnetic order in the quasi-two-dimensional easy-plane XXZ model
• Excitation Spectrum Gap and Spin-Wave Stiffness of XXZ Heisenberg Chains: Global Renormalization-Group Calculation