The Mott Metal-Insulator Transition: Models and Methods

R. Oppermann

Florian Gebhard

Hiroki Nakano, Yoshinori Takahashi

Metal–insulator transition in the ground state of the Hubbard chain with the next-nearest-neighbor hopping is studied by exact diagonalization method. This model shows the partially ferromagnetic metal near the Mott insulator for large Coulomb repulsion while the model reveals the non-magnetic metal for small but finite Coulomb repulsion. We find the transition between the partially ferromagnetic metal and the Mott insulator without phase separation. A new critical exponent of the diverging charge compressibility with respect to the hole density is observed when the system approaches the metal–Mott-insulator transition point from the side of the partially ferromagnetic metal. We also find the occurrence of the phase separation between partially ferromagnetic metal and the Mott insulator for even larger Coulomb repulsion. The model proposed here is interesting in view of the magnetism as well as the metal–insulator transition.

Takuya Yoshioka, Akihisa Koga, Norio Kawakami

Abstract We investigate a metal–insulator Mott transition in the half‐filled Hubbard model on the triangular lattice. In this study, we make use of the path‐integral renormalization group method with an iteration and truncation scheme proposed recently, which allows us to access the competing ground states around the transition point. We find for a cluster with 36 sites that as the Hubbard interaction U increases, the paramagnetic metallic (PM) state undergoes a metal–insulator phase transition to a nonmagnetic insulating (NMI) state at $U_{\rm c} \sim 7.4t$ , where t is the transfer integral. A detailed analysis around the transition point shows that the Mott transition is of first order.

Sindhunil Barman Roy

Arianna Montorsi, Mario Rasetti