title: Ground state of the kagomé-like S=1/2 antiferromagnet volborthite Cu3V2O7(OH)2 x 2H2O.
abstract: The volborthite compound is one of the very few realizations of S=1/2 quantum spins on a highly frustrated kagomé-like lattice. Low-T SQUID measurements reveal a broad magnetic transition below 2 K which is further confirmed by a peak in the 51V nuclear spin relaxation rate (1/T1) at 1.4 K +/- 0.2 K. Through 51V NMR, the ground state (GS) appears to be a mixture of different spin configurations, among which 20% corresponds to a well defined short-range order, possibly of the sqrt(3) x sqrt(3) type. While the freezing involves all the Cu2+ spins, only 40% of the copper moment is actually frozen which suggests that quantum fluctuations strongly renormalize the GS.
authors.affiliation: Laboratoire de Physique des Solides, UMR 8502, Université Paris-Sud, 91405 Orsay, France.
authors.forename: F
authors.initials: F
authors.lastname: Bert
authors.forename: D
authors.initials: D
authors.lastname: Bono
authors.forename: P
authors.initials: P
authors.lastname: Mendels
authors.forename: F
authors.initials: F
authors.lastname: Ladieu
authors.forename: F
authors.initials: F
authors.lastname: Duc
authors.forename: J-C
authors.initials: JC
authors.lastname: Trombe
authors.forename: P
authors.initials: P
authors.lastname: Millet