Tuning frustration in spin liquids by uniaxial pressure

我们探索物质的新量子态，特别是由于强烈的几何受挫而产生的量子自旋液体。几何受挫由原子在晶格中的位置决定，很难在不引入无序的情况下以可控的方式改变。我们全新的实验概念是利用单轴压力系统地改变几何受挫，并以最高精度探测到极低温度下的线性热膨胀。这个量不仅对(磁)相变最敏感，而且对低能激发也最敏感，例如与量子临界性有关。此外，作为与方向相关的熵探测器，它非常适合于研究几何受挫材料的各向异性性质。实施该项目需要在德累斯顿的Max-Planck Institute CPfS开发一种单轴压力膨胀仪，并将其应用于奥格斯堡大学表征的原型材料单晶。我们的主要目标是使用单轴压力来修正几何受挫，将系统调谐到新的量子自旋液体状态，以及探索量子自旋液体对对称破缺扭曲的敏感性。

We explore novel quantum states of matter, in particular quantum spin liquids that arise due to strong geometrical frustration. Geometrical frustration is determined by the location of the atoms in the lattice and can hardly be varied in a controllable way without introducing disorder. Our entirely new experimental concept is to systematically vary geometrical frustration using uniaxial pressure and to detect with highest precision the linear thermal expansion down to very low temperature. This quantity is not only most sensitive to (magnetic) phase transitions but also to low-energy excitations, e.g. related to quantum criticality. Furthermore, as directional dependent probe of the entropy, it is ideally suited to investigate anisotropic properties of geometrically frustrated materials. Implementing the project requires the development of a uniaxial pressure dilatometer at the Max-Planck Institute CPFS in Dresden, as well as its application to single crystals of prototype materials, characterized at Augsburg University. Our main goal is to use uniaxial pressure for modifying geometrical frustration, tuning systems into novel quantum spin liquid states, as well as exploring the sensitivity of quantum spin liquids to symmetry-breaking distortions.