Controlling Emergent Orders in Quantum Materials

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The properties of normal metals and insulators are quite well understood and numerical calculations of the electronic structures provide often astonishing precision, enabling a computational approach to designing materials with a specific property. This level of understanding has been instrumental in the development of semiconductor electronics. Quantum Materials exhibit a vast range of desirable properties, enabling new functionality, however these are usually unexpected and their properties cannot be predicted. Prime examples for the surprising properties of quantum materials are colossal magnetoresistance and high-temperature superconductivity. High temperature superconductivity occurs at temperatures of almost ten times higher than in conventional superconductors (except under pressure), whereas colossal magnetoresistance exhibits a change in resistivity with magnetic field which is orders of magnitude larger than for giant magnetoresistance, for the discovery of which the Nobel prize was awarded in 2007. Reaping the properties of quantum materials for applications has remained elusive, and a lack of understanding of their physics is a major obstacle to achieving this.Reaping the properties of quantum materials for applications has remained elusive. The vast majority of our knowledge about the properties of these materials comes from bulk probes which have provided information about the exotic phases in these materials with exquisite detail. Yet for interfacing to the outside world, it is important to understand the impact of surfaces and interfaces on their emergent properties. The impact of these will provide new opportunities to control their properties, which might lead to entirely new functionalities. For emergent magnetic orders, our knowledge about the impact of the surface in these materials is currently practically zero, therefore this proposal aim to build unique new capability.The here proposed research programme will address this, and lead to(1) An understanding of the impact of surfaces and interfaces on emergent orders, which are critical to technological exploitation(2) Development new methods for atomic scale imaging and characterization of magnetic structure and magnetic excitations(3) Exploration of novel ways to control emergent magnetic states in reduced dimensionalitiesThis will be achieved through a multi-faceted approach combining methods which probe magnetic states at different depths from the surface, thereby enabling a complete characterization of the surface or interface impact on emergent magnetic states.