由于特殊的晶体结构，三角晶格几何阻挫体系可以通过量子涨落阻碍低温长程磁有序的形成，产生量子效应，所以在基础研究和应用领域中该材料都受到广泛关注。层状钙钛矿氧化物(ABO3)是一种简单的三角晶格氧化物，其中长程有序的B离子可以单独形成三角网格, 因此B离子间复杂的相互作用一直是研究的重点。申请人在近期的工作中发现三阶钙钛矿氧化物，Ba3CoSb2O9，存在很强的量子涨落现象，并且该量子涨落会在极端强磁场和高压条件下破坏，产生新的Ising态。本项目中，我们计划采用取代、掺杂的方法，生长新型层状钙钛矿氧化物，运用中子散射、低温热导和比热等实验手段，结合量子蒙特卡洛等理论计算，研究复杂阻挫竞争导致的量子涨落效应、自旋与其它自由度纠缠与竞争所产生的新奇量子态，确定形成机理和稳定性，及不同物态的动力学和输运特性，理解其本征特性与新奇物性的内在联系，为宏观调控量子态物性和设计出新型功能材料打下基础。

Due to the specific crystal structure, the quantum fluctuation could prevent the magnetic long-range-ordering and present the interesting quantum phenomena in geometric frustrated system with triangular lattice, which attract a lot of attentions in scientific and industrial areas. Layered perovskite oxide (ABO3) is one of the triangular lattice oxide and the atomic long-range-ordered B-site ions could build up the triangle frame itself, therefore, most study has been contributed to the complicated interactions between B-ions. Recently, we studied the tri-perovskite, Ba3CoSb2O9, and found that there were strong quantum fluctuations in the system. Moreover, those fluctuations could be broken by the high magnetic field or pressure and lead to the specific Ising state. In this proposal, we plan to synthesize different types of layered perovskite oxide single crystals by replacing or doping on the A- and B-site with the image furnace, and study the complicated competitions, such as the quantum fluctuation effect, interaction(s) between electron, phonon, spin and orbital, in the frustrated system. By combining the techniques of neutron scattering, low temperature thermal conductivity, heat capacity and Monte Carlo simulation, etc., we could obtain the dynamics/transport properties, analyze the intrinsic/abnormal mechanism, and understand the original driving forces of the stability in the frustrated materials. This work should help us control the physical properties and design the advanced functional materials.