Phase transitions in functional materials
Funded by The Spanish Agencia Estatal de Investigación in the project: Rotura de Simetría en Sistemas Electrónicos Topológicos.
Understanding the structural phase transitions of solids and their impact on physical properties is one of the most important tasks in physics. Many functional materials, like ferroelectric or thermoelectric compounds, acquire their fantastic and technologically useful properties after a phase transition. Phase transitions are also crucial in superconductors, as it often appears close to a charge-density wave (CDW) transition, such as in transition-metal dichalcogenides (TMDs), pnictides, or cuprates.
Making use of ab initio calculations with full inclusion of anharmonicity we work on the prediction of CDW transitions in bulk and monolayer TMDs. Our work is crucial to understand the origin of CDW transitions and their sensitivity to dimensionality or other external factors.
We also work on thermoelectric compounds analyzing their phase transitions and the theoretical understanding of their thermal conductivity, which in the most efficient thermoelectric materials requires a non-perturbative treatment of anharmonicity. In fact, strong anharmonicity reduces the thermal conductivity of materials, a requirement to enhance the thermoelectric performance.
Finally, we seek for new topological materials that emerge after a CDW structural phase transition. These materials have very interesting electronic transport properties, such as Hall conductivity, edge and surface states, negative magnetoresistance, and so on, which makes them of enormous technological and industrial interest.