Summary of group activities in 2014

Theoretical condensed-matter physics
Hideo Aoki, Naoto Tsuji

Our main interests are many-body and topological effects in electron and cold-atom systems, i.e., super-conductivity, magnetism and topological phenomena, for which we envisage a materials design and novel non-equilibrium phenomena should be realised. Studies in the 2014 academic year include:

  • Superconductivity
    • High-Tc cuprates: material- and pressure-dependence [1,2]
    • Iron-based superconductors [3]
    • Electron-phonon systems: supersolid and quantum critical point [4]
    • Organic and carbon-based superconductors [1]
    • Fermion and boson systems on flat-band systems
  • Topological systems
    • Topological Mott insulator designed for cold atoms [5]
    • Topological and chiral properties of graphene and silicene [6-8]
    • Graphene quantum dot
  • Non-equilibrium phenomena
    • Non-equilibrium dynamical mean field and dynamical cluster theories [9,10]
    • Floquet topological insulator
    • Relaxation in electron-phonon systems [11]
    • Nonequilibrium quantum spin systems [12]
    • Higgs modes in superconductors [13,14]

[1] H. Aoki and T, Kariyado: Pressure effects and orbital characters in cuprate and carbon-based superconductors, J. Superconductivity and Novel Magnetism 27, 995 (2014).

[2] H. Sakakibara, K. Suzuki, H. Usui, S. Miyao, I. Maruyama, K. Kusakabe, R. Arita, H. Aoki, and K. Kuroki: Orbital mixture effect on the Fermi surface-Tc correlation in the cuprate superconductors — bilayer vs single layer, Phys. Rev. B 89, 224505 (2014).

[3] H. Aoki and H. Hosono: A superconducting surprise comes of age, Physics World, Feb. 2015, p.31.

[4] Y. Murakami, P. Werner, N. Tsuji and H. Aoki: Supersolid phase accompanied by a quantum critical point in the intermediate coupling regime of the Holstein model, Phys. Rev. Lett. 113, 266404 (2014).

[5] S. Kitamura, N. Tsuji and H. Aoki: An interaction-driven topological insulator in fermionic cold atoms on an optical lattice: A design with a density functional formalism, arXiv:1411.3345.

[6] Hideo Aoki and Mildred S. Dresselhaus (eds.): Physics of Graphene (Springer-Verlag, 2014).

[7] H. Aoki and Y. Hatsugai: Polarization as a topological quantum number in graphene, Phys. Rev. B 90, 045206 (2014).

[8] Y. Hatsugai, K. Shiraishi and H. Aoki: Flat bands in Weaire-Thorpe model and silicene, New J. Phys. 17, 025009 (2015).

[9] H. Aoki, N. Tsuji, M. Eckstein, M. Kollar, T. Oka and P. Werner: Nonequilibrium dynamical meanfield theory and its applications, Rev. Mod. Phys. 86, 779 (2014).

[10] N. Tsuji, P. Barmettler, H. Aoki and P. Werner: Nonequilibrium dynamical cluster theory, Phys. Rev. B 90, 075117 (2014).

[11] Y. Murakami, P. Werner, N. Tsuji and H. Aoki: Interaction quench in the Holstein model — Thermalization crossover from electron- to phonon-dominated relaxation, Phys. Rev. B 91, 045128 (2015).

[12] S. Takayoshi, H. Aoki and T. Oka: Many-body Floquet theory of laser-induced phase transition in quantum magnets, Phys. Rev. B 90, 085150 (2014).

[13] R. Matsunaga, N. Tsuji, H. Fujita, A. Sugioka, K. Makise, Y. Uzawa, H. Terai, Z. Wang, H. Aoki, and R. Shimano: Light-induced collective pseudospin precession resonating with Higgs mode in a superconductor, Science 345, 1145 (2014)

[14] N. Tsuji and H. Aoki: Theory of Anderson pseudospin resonance with Higgs mode in a superconductor, arXiv:1404.2711.

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