Research Areas

We study theoretically the electronic states in solids from the viewpoint of topology, and explore the new functions including the non-dissipative currents. Combining the First-principles electronic structure calculations, analytic methods of quantum field theory, and numerical analysis of models for correlated systems, we predict and design the magnetic, optical, transport, and thermal properties of correlated electrons focusing on their internal degrees of freedom such as spin and orbital. Especially, we study extensively the nontrivial interplay between these various properties, i.e., cross-correlation, and develop the new concepts such as electron fractionalization, and non-dissipative quantum operation by considering the topology given by the relativistic spin-orbit interaction and/or spin textures.

Research Subject

1. Theory of spin textures in magnets: In helimagnets, it is possible that the spins show nontrivial configuration, i.e., spin textures. We study theoretically the phase diagram of helimagnets in the plane of magnetic field-temperature. Also the magnetic excitations in each phase are studied.
2. Theory of topological insulators: Topological insulator is a new state of matter, and their physical properties are mostly unexplored yet. We study the transport, optical, and magnetic properties of topological insulators and search for the new possibilities such as the gigantic magneto-electric coupling and new types of excitations. Also the theoretical design of transport phenomena at the interface and junction systems is in progress in terms of the first-principles band structure calculations.
3. Theory of real-time quantum processes: We study the time-dependent quantum dynamics including the conservation law of spins in the presence of tbe spin-orbit interaction, and time-dependent control of spin-orbit interaction. By using the analytic methods as well as the numerical time-dependent quantum simulations, we are aiming to explore the quantum functions utilizing the time-axis.

Related links

1. RIKEN Advanced Science Institute Website_Laboratories Page
2. The University of Tokyo_Nagaosa/Mochizuki Lab Page
3. Correlated Electron Research Group Page
4. Quantum Science on Strong Correlation Page