Direct Measurement of the Bose-Einstein Condensation Universality Class in NiCl(2)-4SC(NH(2))(2) at Ultralow Temperatures

作者：Yin L^*; Xia J S; Zapf V S; Sullivan N S; Paduan Filho A

来源：Physical Review Letters, 2008, 101(18): 187205.

DOI：10.1103/PhysRevLett.101.187205

In this work, we demonstrate field-induced Bose-Einstein condensation (BEC) in the organic compound NiCl(2)-4SC(NH(2))(2) using ac susceptibility measurements down to 1 mK. The Ni S=1 spins exhibit 3D XY antiferromagnetism between a lower critical field H(c1)similar to 2 T and a upper critical field H(c2)similar to 12 T. The results show a power-law temperature dependence of the phase transition line H(c1)(T)-H(c1)(0)=aT(alpha) with alpha=1.47 +/- 0.10 and H(c1)(0)=2.053 T, consistent with the 3D BEC universality class. Near H(c2), a kink was found in the phase boundary at approximately 150 mK.

• 出版日期2008-10-31