2005/05/23 by Vivien S. Zapf, V. S. Zapf, D. Zocco +11 · 219 citations
Materials Science · Physics and Astronomy · #Antiferromagnetism #Bose–Einstein condensate #Boson #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Organic and Molecular Conductors Research #Phase (matter) #Phase diagram #Phase transition #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Spin glass #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.96.077204
published in Physical Review Letters 96(7), 077204 (American Physical Society) · 4 pages, 4 figures
arxiv created 2005/05/23 · openalex publication_date 2006/02/23 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
It has recently been suggested that the organic compound NiCl2-4SC(NH2)2 (DTN) undergoes field-induced Bose-Einstein condensation (BEC) of the Ni spin degrees of freedom. The Ni S = 1 spins exhibit three-dimensional XY antiferromagnetism above a critical field H(c1) approximately 2 T. The spin fluid can be described as a gas of hard-core bosons where the field-induced antiferromagnetic transition corresponds to Bose-Einstein condensation. We have determined the spin Hamiltonian of DTN using inelastic neutron diffraction measurements, and we have studied the high-field phase diagram by means of specific heat and magnetocaloric effect measurements. Our results show that the field-temperature phase boundary approaches a power-law H - H(c1) proportional variant T(alpha)(c) near the quantum critical point, with an exponent that is consistent with the 3D BEC universal value of alpha = 1.5.