Possible Bose-Einstein condensate of magnons in single-crystalline Pb 2 V3 O9

Abstract

We report the growth and the characterization of single crystals of the S=1/2 spin-dimer compound Pb2 V3 O9. Magnetic-susceptibility, torque magnetometry, heat-capacity, and muon-spin-relaxation measurements provide evidence for a field-induced Bose-Einstein condensate of magnons in this system. At low temperatures, the field-dependent phase boundary between the dimerized and the condensed state is well described by the expression T (H-Hc1) 1/φ, with φ= (2.00±0.04). © 2010 The American Physical Society.