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Berezinskii-Kosterlitz-Thouless Phase Transitions with Long-Range Couplings.
Guido Giachetti1, Nicolò Defenu2, Stefano Ruffo3
1SISSA and INFN Sezione di Trieste, Via Bonomea 265, I-34136 Trieste, Italy.
Physical Review Letters
|October 22, 2021
Summary
Long-range couplings significantly alter the Berezinskii-Kosterlitz-Thouless (BKT) transition, introducing a new quasiordered phase. These findings on topological phase transitions are observable in quantum systems.
Area of Science:
- Condensed Matter Physics
- Quantum Phase Transitions
- Statistical Mechanics
Background:
- The Berezinskii-Kosterlitz-Thouless (BKT) transition is a key example of a topological phase transition without symmetry breaking.
- In short-range systems, this transition separates a quasiordered phase from a disordered phase.
Purpose of the Study:
- To investigate the impact of long-range decaying couplings (∼r^{-2-σ}) on the BKT transition.
- To explore the resulting phase diagram and critical phenomena.
Main Methods:
- Theoretical analysis of the BKT transition under long-range interactions.
- Characterization of the phase diagram and critical temperatures.
Main Results:
- Long-range couplings lead to a richer phase diagram compared to short-range models.
- For 7/4 < σ < 2, a novel quasiordered phase emerges between a symmetry-broken and a disordered phase.
- The transition temperature T_{c} exhibits unique universal features distinct from the standard XY model.
Conclusions:
- The study reveals a complex phase structure driven by long-range interactions in topological phase transitions.
- The findings have universal applicability and potential experimental verification in 2D quantum systems.
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