Abstract
is a quantum-spin- system which shows a gap between the singlet ground state of the dimers and the first excited triplet state for magnetic fields . At larger magnetic fields the gap is suppressed, and a Bose-Einstein condensation of triplets is supposed to occur, leading to a magnetic phase with antiferromagnetic long-range order of the transverse spin components. In this study we calculate the fraction of condensed magnetic quasiparticles of from magnetization data. At and right above the critical field , this fraction is of the total number of triplons, and is independent of the direction of the magnetic field if we assume the presence of a small intrinsic magnetic background with magnetic moments.
3 More- Received 3 June 2008
DOI:https://doi.org/10.1103/PhysRevB.78.224403
©2008 American Physical Society