Abstract
We report an experimental determination of the phase boundary approaching the quantum critical point separating a quantum paramagnetic state and the proposed spin Bose-Einstein condensate of triplons in the spin dimer compound . The ordering temperature is related to the proximity to a quantum critical point at the lower critical magnetic field by a power law parametrized by critical exponent . We obtain an experimental estimate of down to a temperature of 0.61 K, which is in good agreement with the mean-field prediction of for the three-dimensional Bose-Einstein condensation universality class.
- Received 5 August 2005
DOI:https://doi.org/10.1103/PhysRevB.72.100404
©2005 American Physical Society