Strain-Tuning of Emergent states of Matter

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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.