title: Bose-Einstein condensation of magnons in Cs2CuCl4.
abstract: We report on results of specific heat measurements on single crystals of the frustrated quasi-2D spin-1/2 antiferromagnet Cs2CuCl4 (T(N)=0.595 K) in external magnetic fields B<12 T and for temperatures T>30 mK. Decreasing B from high fields leads to the closure of the field-induced gap in the magnon spectrum at a critical field Bc approximately = 8.51 T and a magnetic phase transition is clearly seen below Bc. In the vicinity of Bc, the phase transition boundary is well described by the power law Tc(B) proportional, variant (Bc-B)(1/phi), with the measured critical exponent phi approximately =1.5. These findings are interpreted as a Bose-Einstein condensation of magnons.
authors.affiliation: Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Strasse 40, 01187 Dresden, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Radu
authors.forename: H
authors.initials: H
authors.lastname: Wilhelm
authors.forename: V
authors.initials: V
authors.lastname: Yushankhai
authors.forename: D
authors.initials: D
authors.lastname: Kovrizhin
authors.forename: R
authors.initials: R
authors.lastname: Coldea
authors.forename: Z
authors.initials: Z
authors.lastname: Tylczynski
authors.forename: T
authors.initials: T
authors.lastname: Lühmann
authors.forename: F
authors.initials: F
authors.lastname: Steglich