Kadowaki Hiroaki, Wakita Mika, Fåk Björn, Ollivier Jacques, Ohira-Kawamura Seiko, Nakajima Kenji, Lynn Jeffrey W
Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan.
Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex9, France.
Phys Rev B. 2019;99. doi: https://dio.org/10.1103/PhysRevB.99.014406.
Spin correlations of the frustrated pyrochlore oxide Tb Ti O have been investigated by using inelastic neutron scattering on single-crystalline samples ( = -0.007, 0.000, and 0.003), which have the putative quantum-spin-liquid (QSL) or electric-quadrupolar ground states. Spin correlations, which are notably observed in nominally elastic scattering, show short-range correlations around points tiny antiferromagnetic Bragg scattering at and Γ points, and pinch-point-type structures around Γ points. The short-range spin correlations were analyzed using a random-phase approximation (RPA) assuming the paramagnetic state and two-spin interactions among Ising spins. These analyses have shown that the RPA scattering intensity well reproduces the experimental data using temperature- and -dependent coupling constants of up to tenth-neighbor site pairs. This suggests that no symmetry breaking occurs in the QSL sample and that a quantum treatment beyond the semiclassical RPA approach is required. Implications of the experimental data and the RPA analyses are discussed.
通过对具有假定量子自旋液体（QSL）或电四极基态的单晶样品（ = -0.007、0.000和0.003）进行非弹性中子散射，研究了受挫的焦绿石氧化物Tb₂Ti₂O₇的自旋相关性。在名义上的弹性散射中显著观察到的自旋相关性，在 点周围显示出短程相关性，在 点和Γ点处有微小的反铁磁布拉格散射，以及在Γ点周围有捏点型结构。使用假设顺磁态和伊辛自旋之间的双自旋相互作用的随机相位近似（RPA）分析了短程自旋相关性。这些分析表明，RPA散射强度使用高达第十近邻位点对的温度和 依赖耦合常数能很好地再现实验数据。这表明在QSL样品中没有发生对称性破缺，并且需要超越半经典RPA方法的量子处理。讨论了实验数据和RPA分析的意义。
