A direct measurement of the Bose-Einstein Condensation universality class in NiCl${}_2$-4SC(NH${}_2$)${}_2$ at ultra-low temperatures

Abstract

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 $\textsl{S}$=1 spins exhibit 3D $XY$ antiferromagnetism between a lower critical field $H_{c1}\sim$ 2 T and a upper critical field $H_{c2}\sim$ 12 T. The results show a power-law temperature dependence of the phase transition line $H_{c1}(T)-H_{c1}(0)=a{T}^{\alpha }$ with $\alpha =$ 1.47$\pm$0.10 and $H_{c1}(0)=2.053$ T, consistent with the 3D Bose-Einstein Condensation universality class. An abnormal change was found in the phase boundary near $H_{c2}$ at approximately 150 mK.

4 pages, 4 figures

References in corpus (4)

• Bose-Einstein Condensation in Magnetic Insulators
• Dimensional reduction at a quantum critical point
• Bose-Einstein Condensation of Magnons in Cs2CuCl4
• Spin-resonance modes of the spin-gap magnet TlCuCl_3

Cited by in corpus (3)

• Low-Temperature Heat Transport in the Low-Dimensional Quantum Magnet NiCl_{2}-4SC(NH_{2})_{2}
• Interplay of quantum and classical fluctuations near quantum critical points
• Antiferromagnet with two coupled antiferromagnetic sublattices in a magnetic field