Random Exchange Disorder in the Spin-1/2 XXZ Chain

TL;DR

This paper investigates the effects of random exchange disorder in the spin-1/2 XXZ chain, confirming the persistence of a random singlet phase and mapping the zero-temperature phase diagram through numerical simulations.

Contribution

It provides a numerical verification of the random singlet phase in the disordered XXZ chain and maps the phase diagram, comparing results with theoretical predictions.

Findings

Random singlet phase persists with strong XY-symmetric disorder

Zero-temperature phase diagram mapped and matches theoretical predictions

Quasi-long-range order observed in spin-spin correlations

Abstract

The one-dimensional XXZ model is studied in the presence of disorder in the Heisenberg Exchange Integral. Recent predictions obtained from renormalization group calculations are investigated numerically using a Lanczos algorithm on chains of up to 18 sites. It is found that in the presence of strong X-Y-symmetric random exchange couplings, a ``random singlet'' phase with quasi-long-range order in the spin-spin correlations persists. As the planar anisotropy is varied, the full zero-temperature phase diagram is obtained and compared with predictions of Doty and Fisher [Phys. Rev. B {\bf 45 }, 2167 (1992)].