ELECTRONCOMPLEXITY · Emergent complexity in electronically frustrated correlated electron systems
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2007-08-01 → 2011-07-31
- EU contribution
- €1,389,128
- Participants
- 1
- Scheme
- EXT
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Results in brief
Final Activity Report Summary - ELECTRONCOMPLEXITY (Emergent complexity in electronically frustrated correlated electron systems)
One of the most intriguing problems in nature is the change of a system from one phase to another. In condensed matter physics for example, this entails changes from an insulator into a metal or a superconductor, the widest range of change in matter. Notably, many interesting and technologically important materials ranging from field-effect transistors and magneto-restrictive films to superconductors find themselves close to a transition. In this regime, competition between several distinct ground states causes electronic heterogeneity, giving rise to coexistence of different ordered phases separated by one or more critical points. The associated electronic complexity has potential consequences for applications of materials. Here, the behaviour of electrons is strongly correlated to the local environment of the system, because in addition to spin and charge the lattice and orbital degrees of freedoms are active, leading to large responses to small perturbations - a prerequisite for energy friendly, versatile technology. We studied the physics of strongly interacting many-body systems with regard to the occurrence and properties of complex macroscopic states. In the course of this research Programme, we demonstrated the implications of electronic heterogeneity in low dimensional systems with rich phase diagrams including insulating, metallic and superconducting ground states. We introduced a further tuning parameter in our studies, dimensionality, which allowed us for the first time to utilise some of the abovementioned properties to control magnetism at the atomic scale. We also investigated methods to discover putative critical points and novel ground states on the border of magnetism, and the correlation with the physics of short-range phase coherence. Electronically frustrated correlated electron systems can be then tuned to be exactly at or on the cusp of the transition, where electrons behave most collectively, where with tuning of relevant parameters we alter matter to extreme cases.
Data: CORDIS, © European Union
Project objective
The correlation of electrons in a solid produces a variety of states, typically through the interplay between magnetism and electrical conductance. That interplay has itself been a long-standing research topic among condensed matter physicists. But since the discovery of high-temperature superconductors, a more general interest in the Mott transition, the metal-insulator transition (MIT) in a correlated-electron system, has emerged. Close to the MIT, competition between distinct ground states gives rise to spatially extended slow density fluctuations, and coexistence of different ordered phases separated by one or more quantum critical points. Furthermore, the charge, spin, and orbital degrees of freedom, and their coupled dynamics, produce complex phases such as liquid-like, crystal-like, and liquid-crystal-like states of electrons. The behaviours of these systems present profound challenges in fundamental physics, and electronic complexity could have potential consequences for applications because in addition to spin and charge, the lattice and orbital degrees of freedoms are active, leading to large responses to small perturbations. This project will study the nature of quantum order at low temperatures in materials on the border of magnetism and close to a disorder-driven MIT. We will use charge carrier doping as a quantum tuning parameter to investigate the formation of spatially extended density fluctuations and demonstrate the implications of electronic complexity in low dimensional systems. We aim at identifying a physical picture describing the dynamics of spin and charge in materials near disorder-driven MIT's and study the most dramatic consequence of all: the possibility of extended and slow density fluctuations acting in favour of superconducting pairing.
Original text from CORDIS.
Participants
- FOUNDATION OF RESEARCH AND TECHNOLOGY - HELLAS · IRAKLIONCoordinatorGreece
Links
Data: CORDIS, © European Union