In our group, we have studied strongly correlated electron systems (SCES) such as transition metal, actinide and rare earth compounds, in which large Coulomb repulsion plays important role, using both analytic and numerical methods. In SCES, there appear variety of phases in low temperature, for example, magnetism, superconductivity, and charge density wave, etc. The purpose of our group is to obtain a unified picture of these complex systems and to find new physics in such systems.

Our recent subjects are complex orderings due to couplings between electron's spin and orbital degrees of freedom and new quantum mechanical orders in frustrated spin systems. The essential point in frustrated system is that there are a lot of low energy modes and these fluctuations. These consist of, for example, different oscillation modes in space and different fluctuations in the inner degrees of freedom (such as charge, spin, orbital etc.). We are interested in the nature of the order, its critical phenomena, the electron states, and the transport in these systems.

These are our current subjects:

• Electron states in SCES
• Theory of quantum magnets
• Theory of transition, actinide and rare earth conpounds
• Statistical physics in frustrated systems
• Heavy fermion systems

These are our recent studies:

• Superconductivity induced by Ising spin fluctuations under transverse fields
• Optical conductivity in triangluar lattice Hubbard model
• Theory of magnon pair condensation
• Meta-orbital Transition in Heavy-Fermion Systems
• Anharmonic Phonon Mediated Superconductivity and Isomorphic Transition in beta-Pyrochlore Oxides
• Spin Nematic Phase in S=1 Triangular Antiferromagnets
• Magnetism and Electron States on Kagomé Lattice
• Theory of Magnon Crystal
• Theory of Order of Orbitals and Spins in Vanadium Spinels
• Non-Fermi Liquid in S=3/2 Multi-polar Kondo Model

Our recent publications are listed here