Frustration-induced valence bond crystal and its melting in Mo3Sb7.
(121/123)Sb nuclear quadrupole resonance and muon spin relaxation experiments of Mo_3Sb_7 revealed symmetry breakdown to a nonmagnetic state below the transition recently found at T_S approximately 50 K. The transition is characterized by a distinct lattice dynamics suggested from narrowing of nuclear fields. We point out that the Mo sublattice is a unique three-dimensional frustrated lattice where nearest-neighbor and next-nearest-neighbor antiferromagnetic interactions compete, and propose that tetragonal distortion to release the frustration stabilizes long-range order of spin-singlet dimers, i.e., valence bond crystal, which is thermally excited to the dynamic state with cubic symmetry.
Graduate School of Material Science, University of Hyogo, Kamigori, Ako-gun, Hyogo, Japan.
T
T
Koyama
H
H
Yamashita
Y
Y
Takahashi
T
T
Kohara
I
I
Watanabe
Y
Y
Tabata
H
H
Nakamura