大岡山キャンパス 本館2階 H284A 物理学系輪講室
Multiorbital Hubbard systems with Hund coupling exhibit a sharp crossover, as a function of filling or interaction, between a conventional metal state and a non-Fermi liquid metal state with frozen magnetic moments. The fluctuating local moments at the border of this spin-frozen regime induce an instability to a spin-triplet superconducting phase . In multiorbital systems with effectively negative Hund coupling, there is a closely related orbital freezing phenomenon, which is connected to an unconventional type of spin-singlet superconductivity realized in fulleride compounds . In this talk, I will use dynamical mean field simulations to illustrate and discuss these phenomena. By a suitable basis transformation, one can even connect the d-wave superconducting instability in the 2D Hubbard model to a spin-freezing phenomenon .