Observation of phase transition from metal to spin-singlet insulator in MgTi2O4 with S=1/2 pyrochlore lattice
Observation of phase transition from metal to spin-singlet insulator in MgTi2O4 with S=1/2 pyrochlore lattice
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DOI：
10.1143/jpsj.71.1848
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发表时间：
2002-08-01
影响因子：
1.7
通讯作者：
Ueda, Y
中科院分区：
文献类型：
--
作者：
Isobe, M;Ueda, Y
我们已经合成了定义明确的粉末样品的MgTi 2 O 4，这是预期实现烧绿石晶格与S = 1/2，并测量了磁化率，晶格参数和电阻率作为温度的函数。我们发现在260 K附近发生了从金属到自旋单重态绝缘体的相变，并伴随着从立方到四立方的结构转变。这种转变是三维晶格中的一种Peierls转变，这表明与尖晶石结构中嵌入的内部低维密切相关。基态可能是自旋单重态二聚体，理论上预测为烧绿石晶格上S = 1/2海森堡反铁磁体的基态。
We have synthesized well-defined powder samples of MgTi2O4, that are expected to realize the pyrochlore lattice with S = 1/2, and measured the magnetic susceptibility, lattice parameters and resistivity as a function of temperature. We found a phase transition from the metal to the spin-singlet insulator at around 260K, which was accompanied by a structural transformation from cubic to tetragonal. The transition is a kind of Peierls transition in the three-dimensional lattice, which suggests a close relationship to the internal low dimensionality embedded in the spinel structure. The ground state may be spin-singlet dimers theoretically predicted to be the ground state of the S = 1/2 Heisenberg antiferromagnet on the pyrochlore lattice.