Quantum phase transition induced by local defects in Heisenberg spin chains

Random spin- $\frac{3}{2}$ antiferromagnetic Heisenberg chains are investigated using an asymptotically exact renormalization group. Randomness is found to induce a quantum phase transition between two random-singlet phases. In the strong randomness phase the effective spins at low energies are ${S}_{\mathrm{eff}}=\frac{3}{2},$ while in the weak randomness phase the effective spins are ${S}_{\mathrm{eff}}=\frac{1}{2}.$ Separating them is a quantum critical point near which there is a nontrivial mixture of spin- $\frac{1}{2},$ spin- $1,$ and spin- $\frac{3}{2}$ effective spins at low temperatures.Random spin-$\frac{3}{2}$ antiferromagnetic Heisenberg chains are investigated using an asymptotically exact renormalization group. Randomness is found to induce a quantum phase transition between two random-singlet phases. In the strong randomness phase the effective spins at low energies are ${S}_{\mathrm{eff}}=\frac{3}{2},$ while in the weak randomness phase the effective spins are ${S}_{\mathrm{eff}}=\frac{1}{2}.$ Separating them is a quantum critical point near which there is a nontrivial mixture of spin-$\frac{1}{2},$ spin-$1,$ and spin-$\frac{3}{2}$ effective spins at low temperatures.

arXiv:cond-mat/0111295Physical review. B, Condensed matterAug 2, 200251 citations

Phase Transitions and Quantum Correlations in Heisenberg XXZ Spin Chains

Mounaim Hamdoune, Mohammed Daoud A

International Journal of Theoretical PhysicsAug 8, 20260 citations

Random spin-

\frac{3}{2}

antiferromagnetic Heisenberg chains are investigated using an asymptotically exact renormalization group. Randomness is found to induce a quantum phase transition between two random-singlet phases. In the strong randomness phase the effective spins at low energies are

{S}_{\mathrm{eff}}=\frac{3}{2},

while in the weak randomness phase the effective spins are

{S}_{\mathrm{eff}}=\frac{1}{2}.

Separating them is a quantum critical point near which there is a nontrivial mixture of spin-

\frac{1}{2},

spin-

1,

and spin-

\frac{3}{2}

effective spins at low temperatures.