title: Critical properties at the field-induced Bose-Einstein condensation in NiCl(2)-4SC(NH2)2.
abstract: We report new magnetization measurements on the spin-gap compound NiCl(2)-4SC(NH2)2 at the low-field boundary of the magnetic field-induced ordering. The critical density of the magnetization is analyzed in terms of a Bose-Einstein condensation of bosonic quasiparticles. The analysis of the magnetization at the transition leads to the conclusion for the preservation of the U(1) symmetry, as required for Bose-Einstein condensation. The experimental data are well described by quantum Monte Carlo simulations.
authors.affiliation: Instituto de Física, Universidade de São Paulo, 05315-970 SP, Brazil.
authors.forename: A
authors.initials: A
authors.lastname: Paduan-Filho
authors.forename: K A
authors.initials: KA
authors.lastname: Al-Hassanieh
authors.forename: P
authors.initials: P
authors.lastname: Sengupta
authors.forename: M
authors.initials: M
authors.lastname: Jaime