新型S=1/2蜂窝晶格量子磁性材料的单晶制备和磁性研究

由自旋阻挫和量子涨落所导致的量子自旋液体是备受关注的一种量子态，设计与合成具有特殊晶体结构的磁性材料并表征其是否具有量子自旋液体基态是当前凝聚态物理的研究热点之一。本项目拟利用草酸根桥连磁性钴/铱离子，设计合成新型蜂窝晶格磁性系统，并研究这类材料的磁基态，揭示可能存在的量子自旋液体态。项目拟开展工作如下：1）设计合成新型具有钴−草酸框架和铱−草酸框架的蜂窝晶格磁性系统；2）表征样品在不同外加磁场下磁化率和比热随温度的变化规律，探究体系低温下是否存在磁有序转变；针对低温下不存在磁有序的材料，开展极低温、强磁场条件下的电子自旋共振和热导率测量，获得体系的磁激发信息，判断样品是否具有量子自旋液体态，并揭示其微观物理机制；3）总结归纳不同的磁性离子和离子间桥连方式对系统磁基态的影响。

Quantum spin liquid induced by spin frustration and quantum fluctuations is an interesting quantum state. It is a hot topic to design and synthetize magnetic materials with special crystal structure and to characterize whether they have quantum spin liquid state. This project plans to design and synthesize new quantum magnets with honeycomb lattice by oxalate bridging Co2+ or Ir4+ ions, then study the magnetic ground states and reveal the existence of quantum spin liquid states. The main research includes: 1) designing and synthesizing new honeycomb lattice magnetic systems with cobalt-oxalate and iridium-oxalate frameworks; 2) studying the magnetic susceptibility and specific heat dependence on temperature under magnetic fields, and determining the existence of the magnetic transitions at low temperatures. For samples without magnetic transition at low temperature, taking the electron spin resonance and thermal conductivity measurements under ultralow temperature and high magnetic field conditions, investigating the magnetic excitations, determining the existence of the quantum spin liquid state, and revealing the nature of quantum spin liquid; 3) summarizing the effects of different magnetic ions and bridging types on magnetic ground states.