We prove that there exists a class of crystalline insulators, which we call "fragile Mott insulators," which are not adiabatically connected to any sort of band insulator provided time-reversal and certain point-group symmetries are respected, but which are otherwise unspectacular in that they exhibit no topological order nor any form of fractionalized quasiparticles. Different fragile Mott insulators are characterized by different nontrivial one-dimensional representations of the crystal point group. We illustrate this new type of insulators with two examples: the d Mott insulator discovered in the checkerboard Hubbard model at half-filling and the Affleck-Kennedy-Lieb-Tasaki insulator on the square lattice.We prove that there exists a class of crystalline insulators, which we call "fragile Mott insulators," which are not adiabatically connected to any sort of band insulator provided time-reversal and certain point-group symmetries are respected, but which are otherwise unspectacular in that they exhibit no topological order nor any form of fractionalized quasiparticles. Different fragile Mott insulators are characterized by different nontrivial one-dimensional representations of the crystal point group. We illustrate this new type of insulators with two examples: the d Mott insulator discovered in the checkerboard Hubbard model at half-filling and the Affleck-Kennedy-Lieb-Tasaki insulator on the square lattice.

arXiv:1008.1065Physical Review LettersOct 14, 201051 citations

Mott Insulators

Sindhunil Barman Roy

Institute of Physics eBooksJul 1, 201918 citations

Möbius molecules and fragile Mott insulators

Lukas Muechler, Joseph Maciejko, Titus Neupert +1 more

Strongly correlated fermionic systems have been one of the most studied fields in condensed matter theory. The competition between Coulomb-repulsion and kinetic energy leads to a manifold of individual phases, especially in lower dimensions. Famous examples are Luttinger liquids in one dimensions, Mott-insulators or topological phases such as spin liquids. Recently a new class of non-trivial insulators has been introduced, the fragile Mott insulator (FMI). In this paper the authors extend the concept of an FMI to the case of ring-shaped molecules and study the interplay between symmetry, strong correlations as well as strong interactions which ultimately determine the electronic structure of the system.Strongly correlated fermionic systems have been one of the most studied fields in condensed matter theory. The competition between Coulomb-repulsion and kinetic energy leads to a manifold of individual phases, especially in lower dimensions. Famous examples are Luttinger liquids in one dimensions, Mott-insulators or topological phases such as spin liquids. Recently a new class of non-trivial insulators has been introduced, the fragile Mott insulator (FMI). In this paper the authors extend the concept of an FMI to the case of ring-shaped molecules and study the interplay between symmetry, strong correlations as well as strong interactions which ultimately determine the electronic structure of the system.

arXiv:1409.6732Physical Review BDec 23, 20147 citations

Mott Insulators

WORLD SCIENTIFIC eBooksJan 1, 19990 citations

Theory of Mott Insulators

B. H. Brandow

NATO ASI series. Series B : PhysicsJan 1, 19882 citations

Theoretical prediction of fragile Mott insulators on plaquette Hubbard lattices

Han-Qing Wu, Rong-Qiang He, Zi Yang Meng +1 more

Employing extensive cellular dynamical mean-field theory calculations with an exact diagonalization impurity solver, we investigate the ground-state phase diagrams and nonmagnetic metal-insulator transitions of the half-filled Hubbard model on two plaquette (the 1/5 depleted and checkerboard) square lattices. We identify three different insulators in the phase diagrams: dimer insulator, antiferromagnetic insulator, and plaquette insulator. We also demonstrate that the plaquette insulator is a novel fragile Mott insulator (FMI) which features a nontrivial one-dimensional irreducible representation of the ${C}_{4v}$ crystalline point group and cannot be adiabatically connected to any band insulator with time-reversal symmetry. Furthermore, we study the nonmagnetic quantum phase transitions from the metal to the FMI and find that this Mott metal-insulator transition is characterized by the splitting of the noninteracting bands due to interaction effects.Employing extensive cellular dynamical mean-field theory calculations with an exact diagonalization impurity solver, we investigate the ground-state phase diagrams and nonmagnetic metal-insulator transitions of the half-filled Hubbard model on two plaquette (the 1/5 depleted and checkerboard) square lattices. We identify three different insulators in the phase diagrams: dimer insulator, antiferromagnetic insulator, and plaquette insulator. We also demonstrate that the plaquette insulator is a novel fragile Mott insulator (FMI) which features a nontrivial one-dimensional irreducible representation of the ${C}_{4v}$ crystalline point group and cannot be adiabatically connected to any band insulator with time-reversal symmetry. Furthermore, we study the nonmagnetic quantum phase transitions from the metal to the FMI and find that this Mott metal-insulator transition is characterized by the splitting of the noninteracting bands due to interaction effects.

arXiv:1412.7360Physical Review BMar 18, 20157 citations

{C}_{4v}

crystalline point group and cannot be adiabatically connected to any band insulator with time-reversal symmetry. Furthermore, we study the nonmagnetic quantum phase transitions from the metal to the FMI and find that this Mott metal-insulator transition is characterized by the splitting of the noninteracting bands due to interaction effects.