Ground state of the S = 1/2 Heisenberg spin chain with random ferro- and antiferromagnetic couplings

Abstract

We study the Heisenberg $S=1/2$ chain with random ferro- and antiferromagnetic couplings using quantum Monte Carlo simulations at ultra-low temperatures, converging to the ground state. Finite-size scaling of correlation functions and excitation gaps demonstrate an exotic critical state in qualitative agreement with previous strong-disorder renormalization group calculations but with scaling exponents depending on the coupling distribution. We find dual scaling regimes of the transverse correlations versus the distance, with an $L$ independent form $C(r)=r^{-\mu }$ for $r\ll L$ and $C(r,L)=L^{-\eta }f(r/L)$ for $r/L>0$, where $\mu >\eta$ and the scaling function is delivered by our analysis. These results are at variance with previous spin-wave and density-matrix renormalization group calculations, thus highlighting the power of unbiased quantum Monte Carlo simulations.

8 pages, 10 figures

References in corpus (2)

• Quantum-critical scaling properties of the two-dimensional random-singlet state
• Adaptive Density-Matrix Renormalization-Group study of the disordered antiferromagnetic spin-1/2 Heisenberg chain

Cited by in corpus (1)

• Spin-glass quantum phase transition in amorphous arrays of Rydberg atoms