The main issue focused in this fellowship is related to the current electronic devices, such as tablets, cell phones and computers, efficiency. Inside these devices, there are two types of electrons (which are small particles): the free electrons and the localized electrons. The localized electrons hold small pieces of information (spin) and create a memory for the current devices, in this way images and files can be stored. On the other hand, the free electrons are responsible for powering the devices by carrying around small packages of energy (charge) and changing the information stored in the localized ones. Both types of electrons interact with each other, either by colliding or just by feeling the presence of the other. These interactions are called correlations and are an important property for the efficiency of the devices. Another useful property is the path that the free electrons choose to carry information or energy. Some paths result in fast and organized movement of electrons while others can be slower and more complicated, wasting power. The shape of the paths or surfaces chosen can be associated to topology. The interplay between correlations and topology is not yet fully understood and is a promising area for the development of new and more efficient electronic devices. Therefore, in this project we have studied materials to enhance the knowledge on the edge of these two fundamental areas: strong correlations and topology. These studies are of great importance to the society as they are fundamental to the creation of better and more efficient electronic devices. Therefore, the research performed presented a great importance for the development of innovations and for creating/enabling clean and sustainable energy for the society, which fits in the UN sustainable development goals.
The main objectives of this research were to perform electrical resistivity experiments under hydrostatic compression or uniaxial strain in strongly correlated electron systems. These experiments are similar to what happens inside a pressure cooker or when we use a rubber band. By mechanically compressing things in all directions (pressure cooker) or in one direction (rubber band), we can change the properties of materials. For example, in the pressure cooker, the water boils at a higher temperature, so the food cooks faster. In the rubber band, when we pull, the band gets thinner or thicker. But instead of preparing a dish faster or holding things together we aimed to change the properties of materials by compressing in all directions (hydrostatic pressure) or by pushing and pulling in one direction (uniaxial strain).
