Spin structure factor and quantum phases of frustrated spin-1/2 chains

TL;DR

This paper investigates the spin structure factor in frustrated spin-1/2 chains, revealing how quantum phases and correlations manifest through divergence or finiteness at specific wave vectors, and identifies phase transitions via numerical methods.

Contribution

It provides detailed numerical analysis of the static structure factor to distinguish quantum phases and phase transitions in frustrated spin chains with isotropic exchange.

Findings

Divergence of S(q) at q_m indicates quasi-long-range order.

Finite S(q_m) characterizes bond-order-wave phases.

Identification of a decoupled phase with q_m = π/2 in certain chains.

Abstract

The static structure factor S(q) of frustrated spin-1/2 chains with isotropic exchange and a singlet ground state (GS) diverges at wave vector q_m when the GS has quasi-long-range order (QLRO) with periodicity 2\pi/q_m but S(q_m) is finite in bond-order-wave (BOW) phases with finite-range spin correlations. Exact diagonalization and density matrix renormalization group (DMRG) calculations of S(q) indicate a decoupled phase with QLRO and q_m = \pi/2 in chains with large antiferromagnetic exchange between second neighbors. S(q_m) identifies quantum phase transitions based on GS spin correlations.