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Phys. Rev. B 68, 060402 (2003) [4 pages]

Field-induced XY behavior in the S=1 / 2 antiferromagnet on the square lattice

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Alessandro Cuccoli1,2, Tommaso Roscilde1,2, Ruggero Vaia3,2, and Paola Verrucchi1,2
1Dipartimento di Fisica dell’Università di Firenze—via G. Sansone 1, I-50019 Sesto Fiorentino (FI), Italy
2Istituto Nazionale per la Fisica della Materia—U.d.R. Firenze—via G. Sansone 1, I-50019 Sesto Fiorentino (FI), Italy
3Istituto di Fisica Applicata “Nello Carrara” del Consiglio Nazionale delle Ricerche—via Panciatichi 56/30, I-50127 Firenze, Italy

Rapid Communication Received 21 February 2003; published 12 August 2003

Making use of the quantum Monte Carlo method based on the worm algorithm, we study the thermodynamic behavior of the S=1 / 2 isotropic Heisenberg antiferromagnet on the square lattice in a uniform magnetic field varying from very small values up to the saturation value. The field is found to induce a Berezinskii-Kosterlitz-Thouless transition at a finite temperature, above which genuine XY behavior in an extended temperature range is observed. The phase diagram of the system is drawn, and the thermodynamic behavior of the specific heat and of the uniform and staggered magnetization is discussed in sight of an experimental investigation of the field-induced XY behavior.


©2003 The American Physical Society

URL: http://link.aps.org/abstract/PRB/v68/e060402
DOI: 10.1103/PhysRevB.68.060402
PACS: 75.10.Jm, 05.30.-d, 75.40.Cx

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