Quantum effects on the Berezinskii-Kosterlitz-Thouless transition in the ferromagnetic two-dimensional {ital XXZ} model

Journal Article · Mon May 01 00:00:00 EDT 1995 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.51.12840· OSTI ID:44586

Cuccoli, A; Tognetti, V; Verrucchi, P ^[1]; Vaia, R ^[2]

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1. Dipartimento di Fisica dell`Universita di Firenze, Largo Enrico Fermi 2, I-50125 Firenze (Italy)
2. Istituto di Elettronica Quantistica del Consiglio Nazionale delle Ricerche, Via Panciatichi 56/30, I-50127 Firenze (Italy)

The quantum easy-plane ferromagnetic two-dimensional {ital XXZ} model is approached by the pure-quantum self-consistent harmonic approximation that reduces it to an effective classical model. Quantum fluctuations weaken both the effective exchange, leading to a reduced Berezinskii-Kosterlitz-Thouless transition temperature with respect to the classical model, and the effective easy-plane anisotropy. The latter vanishes when the anisotropy is smaller than a cutoff value, leading to an instability that could be interpreted as a crossover to a strongly quantum regime where a picture of classical-like renormalized vortices is inadequate.

• OSTI ID: 44586
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 18 Vol. 51; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CRYSTAL MODELS
FERROMAGNETISM
FLUCTUATIONS
INSTABILITY
KOSTERLITZ-THOULESS THEORY
QUANTIZATION
TRANSITION TEMPERATURE
TWO-DIMENSIONAL CALCULATIONS