title: Order by disorder from nonmagnetic impurities in a two-dimensional quantum spin liquid.
abstract: We consider doping of nonmagnetic impurities in the spin-1/2, 1/5-depleted square lattice. This structure, whose undoped phase diagram offers both magnetically ordered and spin-liquid ground states, is realized physically in CaV4O9. Doping into the ordered phase results in a progressive loss of order, which becomes complete at the percolation threshold. By contrast, doping into the spin liquids creates a phase of weak but long-ranged antiferromagnetic order, a true order-by-disorder phenomenon. We study the phase diagram of the doped system by computing the static susceptibility and staggered magnetization using a stochastic series-expansion quantum Monte Carlo technique.
authors.affiliation: Department of Physics and Astronomy, University of Southern California, Los Angeles 90089-0484, USA.
authors.forename: S
authors.initials: S
authors.lastname: Wessel
authors.forename: B
authors.initials: B
authors.lastname: Normand
authors.forename: M
authors.initials: M
authors.lastname: Sigrist
authors.forename: S
authors.initials: S
authors.lastname: Haas