title: Possible spin singlet quadrumerization in Pb2Re2O(7-δ).
abstract: A single crystal of pyrochlore Pb(2)Re(2)O(6.75) was prepared by hydrothermal synthesis, and its magnetic and transport properties were investigated. Pb(2)Re(2)O(6.75) shows the metallic conduction with an anomalous second-order structural phase transition at T(s)=294 K, in which the magnetization and the structure change similarly to that at 200 K of the superconductor Cd(2)Re(2)O(7). A three-dimensional Ising-like order parameter probed by the atomic displacement suggests that an unconventional spin singlet state is possibly realized in the ground state of Pb(2)Re(2)O(6.75), in which four spins make a quadrumer in order to remove the spin frustration of the pyrochlore lattice.
authors: Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan. michioka@kuchem.kyoto-u.ac.jp
authors: C
authors: C
authors: Michioka
authors: Y
authors: Y
authors: Kataoka
authors: H
authors: H
authors: Ohta
authors: K
authors: K
authors: Yoshimura