Berlin 2024 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 61: Correlated Electrons: 1D Theory

TT 61.4: Vortrag

Mittwoch, 20. März 2024, 17:15–17:30, H 3010

Valence-bond order in quantum spin chains with a dissipative spin-Peierls coupling — •Manuel Weber — Institut für Theoretische Physik and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, Germany

Quantum spin chains exhibit critical phases of matter that might become unstable when coupled to environmental degrees of freedom. Here, we study the effect of bond dissipation on the one-dimensional antiferromagnetic spin-1/2 Heisenberg model. In analogy to the spin-Peierls problem, the dissipative bath is described by local harmonic oscillators that modulate the spin exchange coupling, but instead of a single boson frequency we consider a continuous bath spectrum ∝ ω^s. Using an exact quantum Monte Carlo method for retarded interactions, we show that for s<1 any finite coupling to the bath induces valence-bond-solid order, whereas for s>1 the critical phase of the isolated chain remains stable up to a finite critical coupling. We find that, even in the presence of the gapless bosonic spectrum, the spin-triplet gap remains well defined for any system size, from which we extract a dynamical critical exponent of z=1. We provide evidence for a Berezinskii-Kosterlitz-Thouless quantum phase transition that is governed by the SU(2)₁ Wess-Zumino-Witten model. Our results suggest that the critical properties of the dissipative system are the same as for the spin-Peierls model, irrespective of the different interaction range, i.e., power-law vs. exponential decay, of the retarded dimer-dimer interaction, indicating that the spin-Peierls criticality is robust with respect to the bosonic density of states.