Critical properties at the field-induced Bose-Einstein condensation in NiCl(2)-4SC(NH2)2.
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.
Paduan-Filho
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Instituto de Física, Universidade de São Paulo, 05315-970 SP, Brazil.
Al-Hassanieh
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Sengupta
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Jaime
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