量子自旋阻挫体系与量子自旋液体

Frustrated Quantum Spin Systems and Quantum Spin Liquids

量子自旋液体是量子磁性系统中的新型物质形态,一般认为这种新物态源于阻挫相互作用。由于强烈的量子涨落导致基态呈磁无序状态,其低能激发不是通常的自旋波,而是分数化的自旋子和演生的规范涨落。经过几十年的积累,量子自旋液体在分类理论、数值计算和材料合成、物性测量等方面取得了丰富的成果。在国内,实验方面在三角晶格上的自旋轨道耦合材料YbMgGaO4、笼目晶格上的材料ZnCu3(OH)6FBr和ZnCu3(OH)6FCl、六角晶格上的Kitaev材料α-RuCl3等阻挫系统的研究中取得突破性进展,部分达到国际领先水平;理论方面,在计算笼目格子海森堡模型的基态、刻画具有自旋轨道耦合的阻挫模型的相图、构造非对易自旋液体模型、建立自旋液体低能有效理论等方面也取得重要进展。由于强关联系统的复杂性,自旋液体领域仍然有很多重大问题尚未完全解决。另一方面,鉴于这一领域的重要性,我们需要集聚力量、协同合作,在材料、实验和理论上取得新的突破,推进相关领域的持续性发展。

Quantum spin liquid is a new phase of matter in quantum magnetic system, whose ground state is magnetically disordered owing to strong quantum fluctuations caused by frustrated interaction, and whose low energy excitations are fractionalized spinons and emergent gauge fluctuations instead of usual spin waves. After decades of studies, fruitful progresses have been made in theoretical classification, numerical simulation and compound synthesis, physical-property measurements and so on. In China, breakthroughs have been made in the research of spin-orbital coupled triangular material YbMgGaO4, Kagome material ZnCu3(OH)6FBr and ZnCu3(OH)6FCl, and the Kitaev material α-RuCl3 on Honeycomb. Some domestic contributions are at the level of world first-class. In the theoretical side, important progress has been made in various aspects, including computing the ground state of anti-ferromagnetic Heisenberg model on Kagome lattice, figuring out the phase diagram of spin-orbital coupled frustrated models, constructing models to realize non-Abelian spin liquids, setting up low-energy effective theory, and so on. Owing to the complexity of the strong interaction, many important issues of quantum spin liquids are still not completely solved. On the other hand, owing to its significance, we need to keep collaborating so as to make more important breakthroughs in new material synthesis, property characterizations and theoretical representations, which will significantly promote the development of those fields related to the quantum spin liquid.