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arXiv · 2209.01182

Continuously varying critical exponents in long-range quantum spin ladders

P. Adelhardt·K. P. Schmidt
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Abstract

We investigate the quantum-critical behavior between the rung-singlet phase with hidden string order and the N\'eel phase with broken $SU(2)$-symmetry on quantum spin ladders with algebraically decaying unfrustrated long-range Heisenberg interactions. Combining perturbative continuous unitary transformations (pCUT) with a white-graph expansion and Monte Carlo simulations yields high-order series expansions of energies and observables in the thermodynamic limit about the isolated rung-dimer limit. The breakdown of the rung-singlet phase allows to determine the critical line and the entire set of critical exponents as a function of the decay exponent of the long-range interaction. A non-trivial regime of continuously varying critical exponents as well as long-range mean-field behavior is demonstrated reminiscent of the long-range transverse-field Ising model.

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P. Adelhardt, K. P. Schmidt. 2022-09-02. Continuously varying critical exponents in long-range quantum spin ladders. https://arxiv.org/abs/2209.01182

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