The quasilinear bands in the topologically trivial skutterudite insulator CoSb(3) are studied under adiabatic, symmetry-conserving displacement of the Sb sublattice. In this cubic, time-reversal and inversion symmetric system, a transition from trivial insulator to topological point Fermi surface system occurs through a critical point in which massless (Dirac) bands appear, and moreover are deg...

A structural phase transition has been found using electron diffraction technique in PrRu4P12 accompanied by a metal insulator (M I) transition (TMI = 60K). Weak superlattice spots appeared at (H, K, L) (H + K + L = 2n + 1; n is an integer) position at a temperature of T = 12 K and 40 K. Above T = 70 K, the spots completely vanished. The space group of the low temperature phase is probably Pm 3...

Moir\'e superlattices formed in two-dimensional semiconductor heterobilayers provide a new realization of Hubbard model physics which the number electrons per effective atom can be tuned at will. We report on an exact diagonalization study electronic properties half-filled narrow moir\'e bands correlation strengths are varied by changing twist angles or interaction strengths. construct phase di...

The evolution from an anomalous metallic phase to a Mott insulator within the two-dimensional Hubbard model is investigated by means of the cellular dynamical mean-field theory. We show that approaching the density-driven Mott metal-insulator transition the Fermi surface is strongly renormalized and the quasiparticle description breaks down in a very anisotropic fashion. Regions where the quasi...

We study the quantum phase transition between a band (“ionic”) insulator and a Mott-Hubbard insulator, realized at a critical value U = Uc in a bipartite Hubbard model with two inequivalent sites, whose on-site energies differ by an offset ∆. The study is carried out both in D = 1 and D = 2 (square and honeycomb lattices), using exact Lanczos diagonalization, finitesize scaling, and Berry’s pha...

A few electrons per ion scenario for the B = 0 metal-insulator transition in two dimensions Abstract We argue on the basis of experimental numbers that the B = 0 metal-insulator transition in two dimensions, observed in Si-MOSFETs and in other two-dimensional systems, is likely to be due to a few strongly interacting electrons, which also interact strongly with the random positively ionized imp...