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Magnetic quasi-long-range ordering in nematic systems due to competition between higher-order couplings
Milan Žukovič1, Georgii Kalagov1
1Institute of Physics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9, 041 54 Košice, Slovakia.
Physical Review. E
|June 17, 2018
Summary
The coexistence of nematic-like terms in the 2D XY model creates a magnetic quasi-long-range order phase. This competition leads to two phase transitions, with critical properties belonging to Ising and three-state Potts universality classes.
Area of Science:
- Condensed Matter Physics
- Statistical Mechanics
- Phase Transitions
Background:
- The two-dimensional XY model is a fundamental model in statistical mechanics, often studied for magnetic ordering.
- Nematic-like terms, distinct from purely magnetic interactions, can influence the model's phase behavior.
- Understanding the interplay of competing interactions is crucial for predicting emergent phenomena in physical systems.
Purpose of the Study:
- To investigate the critical properties of the 2D XY model with second and third-order nematic-like terms.
- To determine the nature of magnetic ordering and phase transitions induced by these competing interactions.
- To analyze the universality classes governing the observed phase transitions.
Main Methods:
- Spin-wave analysis to probe low-energy excitations and magnetic properties.
- Monte Carlo simulations to model the system's behavior and identify phases.
- Finite-size scaling analysis to determine critical exponents and universality classes.
Main Results:
- Coexistence of second and third-order nematic-like terms induces a magnetic quasi-long-range order phase.
- This magnetic phase is situated between two distinct nematic-like phases.
- Two sequential phase transitions occur: paramagnetic to nematic-like, then to magnetic.
- Transitions belong to the Ising and three-state Potts universality classes.
- Spin-pair correlation decays slower than in standard XY models, with low vortex-antivortex density.
Conclusions:
- The competition between nematic-like terms is essential for generating magnetic ordering in this model.
- The system exhibits complex phase diagrams with multiple transitions and distinct universality classes.
- The observed magnetic phase displays unique characteristics, including slow correlation decay and suppressed vortex-antivortex pairs.
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