COVER

摘要

Three possible phases of the kagome Heisenberg antiferromagnet, a model of geometrically "frustrated" magnetism: the diamond-pattern valence bond crystal (lower left), honeycomb valence bond crystal (lower right), and quantum spin liquid (upper empty wedge). Deviations of bond strengths from their average values are shown by bond widths and colors (red, stronger; blue, weaker). The simulations of Yan et al. (p. 1173) show that the true ground-state phase is the quantum spin liquid.