Using the Hubbard chain at quarter filling as a model system, we study the ground state properties of highly doped antiferromagnets. In particular, the Hubbard chain at quarter filling is unstable against $2{k}_{F}$ - and $4{k}_{F}$ -periodic potentials, leading to a large variety of charge and spin ordered ground states. Employing the density matrix renormalization group method, we compare the energy gain of the ground state induced by different periodic potentials. For interacting systems the lowest energy is found for a $2{k}_{F}$ -periodic magnetic field, resulting in a band insulator with spin gap. For strong interaction, the $4{k}_{F}$ -periodic potential leads to a half-filled Heisenberg chain and thus to a Mott insulating state without spin gap. This ground state is more stable than the band insulating state caused by any non-magnetic $2{k}_{F}$ -periodic potential. Adding more electrons, a cluster-like ordering is preferred.Using the Hubbard chain at quarter filling as a model system, we study the ground state properties of highly doped antiferromagnets. In particular, the Hubbard chain at quarter filling is unstable against $2{k}_{F}$- and $4{k}_{F}$-periodic potentials, leading to a large variety of charge and spin ordered ground states. Employing the density matrix renormalization group method, we compare the energy gain of the ground state induced by different periodic potentials. For interacting systems the lowest energy is found for a $2{k}_{F}$-periodic magnetic field, resulting in a band insulator with spin gap. For strong interaction, the $4{k}_{F}$-periodic potential leads to a half-filled Heisenberg chain and thus to a Mott insulating state without spin gap. This ground state is more stable than the band insulating state caused by any non-magnetic $2{k}_{F}$-periodic potential. Adding more electrons, a cluster-like ordering is preferred.

arXiv:cond-mat/0701235Physical Review BJan 24, 20076 citations

On the lowest-energy excitations of one-dimensional strongly correlated electrons

K. Kladko

It is proven that the lowest excitations E low ( k ) of one-dimensional half-integer spin generalized Heisenberg models and half-filled extended Hubbard models are π-periodic functions. For Hubbard models at fractional fillings E low ( k + 2 k f ) = E low ( k ), where 2 k f = π n , and n is the number of electrons per unit cell. Moreover, if one of the ground states of the system is magnetic in the thermodynamic limit, then E low ( k ) = 0 for any k , so the spectrum is gapless at any wave vector. The last statement is true for any integer or half-integer value of the spin.It is proven that the lowest excitations E low ( k ) of one-dimensional half-integer spin generalized Heisenberg models and half-filled extended Hubbard models are π-periodic functions. For Hubbard models at fractional fillings E low ( k + 2 k f ) = E low ( k ), where 2 k f = π n , and n is the number of electrons per unit cell. Moreover, if one of the ground states of the system is magnetic in the thermodynamic limit, then E low ( k ) = 0 for any k , so the spectrum is gapless at any wave vector. The last statement is true for any integer or half-integer value of the spin.

arXiv:cond-mat/9803073Europhysics Letters (EPL)Feb 1, 19990 citations

Ground state properties of half-filled Hubbard model

Canio Noce, Mario Cuoco

Physics Letters AJul 1, 19971 citation

On the ground state of the half-filled Hubbard model

B. Mehlig, Peter Fulde

The European Physical Journal BSep 1, 19944 citations

2{k}_{F}

- and

4{k}_{F}

-periodic potentials, leading to a large variety of charge and spin ordered ground states. Employing the density matrix renormalization group method, we compare the energy gain of the ground state induced by different periodic potentials. For interacting systems the lowest energy is found for a

2{k}_{F}

-periodic magnetic field, resulting in a band insulator with spin gap. For strong interaction, the

4{k}_{F}

-periodic potential leads to a half-filled Heisenberg chain and thus to a Mott insulating state without spin gap. This ground state is more stable than the band insulating state caused by any non-magnetic

2{k}_{F}

-periodic potential. Adding more electrons, a cluster-like ordering is preferred.