An Impurity Driven Phase Transition in the Antiferromagnetic Spin-1 Chain

TL;DR

This paper demonstrates that introducing impurities in a Heisenberg antiferromagnetic spin-1 chain induces a second order phase transition from the Haldane phase to a random singlet phase, characterized by a Griffiths region and specific critical exponents.

Contribution

It provides an asymptotically exact real space renormalization analysis revealing impurity-driven phase transition mechanisms in spin chains.

Findings

Identifies a second order phase transition driven by impurities.

Characterizes the Griffiths region with diverging susceptibility.

Determines the correlation length critical exponent as approximately 2.3.

Abstract

Using an asymptotically exact real space renormalization procedure, we find that the Heisenberg antiferromagnetic spin-1 chain undergoes an impurity driven second order phase transition from the Haldane phase to the random singlet phase, as the bond distribution is broadened. In the Haldane phase and near the critical point, there is a Griffiths region in which the gap is filled and the susceptibility diverges in a non-universal manner. The correlation length critical exponent is approximately 2.3.