Strain-Tuning of Emergent states of Matter

未来的技术，如自旋电子学或集成量子传感器，不仅需要具有出色的电子性能，而且还需要具有复杂的磁性和结构功能的材料。有可能在这些技术中发挥关键作用的一大类化合物是“量子材料”。最重要的共同点是这些材料的性质由典型的量子力学现象决定，例如稳定由电子-电子相互作用驱动的相干许多体相。这些真正先进的材料的物理学是由不同的竞争磁性，电荷和轨道自由度之间的强烈相互作用所决定的，这些现象往往对我们目前的理解水平构成根本挑战。我们的建议的一个核心特征是，大量竞争或合作的电荷和自旋顺序导致量子材料的物理性质的极端可调性-它们对外部刺激高度敏感。这种灵敏度当然使它们对于需要控制电流、磁性或感测环境参数的应用非常有吸引力。在这里，我们将利用这种可调性通过单轴应变，一个关键的控制参数，最近已受到越来越多的关注。它通过晶格应变进行选择性对称性控制的能力在强烈改变超导转变温度、稳定全新的相位或通过对称性控制改变电荷和自旋密度波之间的耦合方面非常成功。量子材料中应变稳定电子态的研究在技术上非常具有挑战性，需要理想地原位应变调谐和电子态的光谱表征。我们最近成功地结合原子分辨光谱成像的材料的电子性质的扫描隧道显微镜原位调谐单轴应变。这为我们研究应变对紧急订单和电子结构的影响的能力提供了一个步骤。应变稳定相的性质的宏观测量的原子尺度表征的组合将提供新的见解，在原子尺度上发现的微观物理和材料的宏观性质之间的相互作用。它还将使我们能够确定新的方法来操纵物质的紧急阶段使用单轴应变。

Future technologies such as spintronics or integrated quantum sensors require materials that do not only have outstanding electronic properties but incorporate intricate complex magnetic and structural functionalities. One large class of compounds that has the potential to play a key role in such technologies are 'Quantum Materials'. The overarching commonality is that the properties of these materials are governed by quintessential quantum mechanical phenomena e.g. stabilising coherent many body phases which are driven by electron-electron interactions. The physics of these truly advanced materials is governed by a strong interplay between different competing magnetic, charge and orbital degrees of freedom with the emergent phenomena often posing a fundamental challenge to our current level of understanding. A feature central to our proposal is that the large number of competing or cooperating charge and spin orders result in an extreme tunability of the physical properties of quantum materials - they are highly sensitive to external stimuli. This sensitivity of course makes them very attractive for applications which require controlling currents, magnetism or sensing environmental parameters. Here we will exploit this tunability through uniaxial strain, a key control parameter which has received increased attention recently. Its capability for selective symmetry control by lattice straining has been very successful in strongly changing superconducting transition temperatures, stabilising completely new phases, or changing the coupling between charge and spin density waves by symmetry control. A study of the strain-stabilized electronic states in quantum materials is technologically very challenging, requiring ideally in-situ strain tuning and spectroscopic characterization of the electronic states. We recently succeeded in combining atomically resolved spectroscopic imaging of the electronic properties of materials by scanning tunnelling microscopy with in-situ tuning of uniaxial strain. This provides a step change in our capabilities to study the impact of strain on emergent orders and the electronic structure. Combination of the atomic-scale characterization with macroscopic measurements of the properties of the strain stabilized phases will provide new insights into the interplay between the microscopic physics found at the atomic scale and macroscopic properties of the material. It will also enable us to identify new ways to manipulate emergent phases of matter using uniaxial strain.