Field-free quantum-spin-1/2 XXZ model in three-dimensions: phases, phase transitions, and phase diagrams by renormalization group theory

Authors : Ozan Sabahattin SARIYER

Pages : 288-301

Doi:10.3906/fiz-2002-24

View : 17 | Download : 3

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The field-free quantum-spin-1/2 XXZ model is studied in three-dimensions using renormalization group theory. We obtain global phase diagrams and critical properties. We identify zero-temperature quantum phase transitions at isotropic points, as well as long-range order below critical temperatures at all anisotropies. We show that the excitation spectrum is gapless in XY-like, and gapped in Ising-like anisotropy regimes. Besides, internal energy density, specific heat, nearest-neighbor entanglement measures and spin-spin correlations are obtained globally at all temperatures. Our numerical results cover the global range of anisotropy parameter, for both ferromagnetic and antiferromagnetic cases.
Keywords : Statistical mechanics of spin systems, renormalization group theory, thermodynamic functions, quantum entanglement, classical and quantum magnetic phase transitions