https://doi.org/10.1007/BF01313912
Phase transitions in two-dimensional anisotropic quantum magnets
1
Dipartimento
di Fisica dell'Università di Firenze and Istituto Nazionale di
Fisica della Materia (INFM), Largo E. Fermi 2, 50125 Firenze,
Italy
2
Dipartimento di Fisica "A. Volta"dell'Università di Pavia and INFM,
via Bassi 6, 27100 Pavia, Italy
3
Istituto di Elettronica Quantistica
del Consiglio Nazionale delle Ricerche and INFM,
via Panciatichi 56/30, 50127 Firenze, Italy
Corresponding author: a tognetti@fi.infn.it
Received:
13
October
2000
Published online: 15 March 2001
We consider quantum Heisenberg ferro- and antiferromagnets on the square lattice with exchange anisotropy of easy-plane or easy-axis type. The thermodynamics and the critical behaviour of the models are studied by the pure-quantum self-consistent harmonic approximation, in order to evaluate the spin and anisotropy dependence of the critical temperatures. Results for thermodynamic quantities are reported and comparison with experimental and numerical simulation data is made. The obtained results allow us to draw a general picture of the subject and, in particular, to estimate the value of the critical temperature for any model belonging to the considered class.
PACS: 75.10.Jm – Quantized spin models / 75.10.-b – General theory and models of magnetic ordering / 75.40.Cx – Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001
