Related papers: Simultaneous Charge Ordering and Spin Dimerization…
We investigate the ground-state phase diagram of the quarter-filled Hubbard ladder with nearest-neighbor Coulomb repulsion V using the Density Matrix Renormalization Group technique. The ground-state is homogeneous at small V, a…
Recent X-ray analysis and NMR- experiments have shown that alpha'- NaV2O5 is not a conventional spin-Peierls (SP) compound because above the transition at 33K it is in a homogeneous mixed valent (MV) state and atomic spin chains do not…
Based on recent experimental evidences that the electronic charge degrees of freedom plays an essential role in the spin-Peierls--like phase transition of NaV$_2$O$_5$, we first make the mapping of low-energy electronic states of the…
We study the quantum transition from a strongly correlated metal, with heavy fermionic quasiparticles, to a metal with commensurate charge or spin density wave order. To this end, we introduce and numerically analyze a large dimensionality…
Using quantum Monte Carlo simulations and field-theory arguments, we study the fully frustrated (Villain) transverse-field Ising model on the square lattice. We consider a "primary" spin order parameter and a "secondary" dimer order…
We studied quantum phase transitions in the antiferromagnetic dimerized spin-1/2 XY chain andvtwo-leg ladders. From analysis of several spin models we present our main result: the framework to deal with topological orders and hidden…
The phase diagram of a frustrated S=1/2 antiferromagnetic spin ladder with additional next-nearest neighbor exchanges, both diagonal and inchain, is studied by a weak-coupling effective field theory approach combined with exact…
We consider self-dual transverse-field Ising spin chains with $m$-spin interaction, where the phase transition is of second and first order, for m <= 3 and m>3, respectively. We present a statistical analysis of the spectra of the…
We suggest that the phase transition observed in NaV_2O_5 at T_c = 34K is not a spin-Peierls transition, but a charge ordering transition, related to the formal presence in this system of equal number of V^4+ and V^4- ions. Below T_c, V^4+…
The nature of electronic states due to strong correlation and geometric frustration on the triangular lattice is investigated in connection to the unconventional insulating state of Na$_x$CoO$_2$ at $x=0.5$. We study an extended Hubbard…
We explore nonadiabatic quantum phase transitions in an Ising spin chain with a linearly time-dependent transverse field and two different spins per unit cell. Such a spin system passes through critical points with gapless excitations,…
We investigate charge ordering in the presence of electron-phonon coupling for quarter-filled ladder systems by using Exact Diagonalization. As an example we consider NaV2O5 using model parameters obtained from first-principles…
Motivated by recent experiments on quasi-1D vanadium oxides, we study quantum phase transitions in a one-dimensional spin-orbital model describing a Haldane chain and a classical Ising chain locally coupled by the relativistic spin-orbit…
We present a detailed analysis of light scattering experiments performed on the quarter-filled spin ladder compound $\alpha^\prime$-NaV$_{2}$O$_{5}$ for the temperature range 5 K$\le$T$\le$300 K. This system undergoes a phase transition…
We present Density Matrix Renormalization Group calculations of the ground-state properties of quarter-filled ladders including static electron-lattice coupling. Isolated ladders and two coupled ladders are considered, with model parameters…
The low-temperature electronic and magnetic properties of NH$_4$V$_2$O$_5$, an isoelectronic analog of the spin-ladder compound $\alpha'$-NaV$_2$O$_5$, are investigated using DFT+$U$ calculations. Two charge-ordering patterns - zigzag and…
Ground-state behaviour of the frustrated quantum spin-1/2 two-leg ladder with the Heisenberg intra-rung and Ising inter-rung interactions is examined in detail. The investigated model is transformed to the quantum Ising chain with composite…
We revisit the phase diagram of the dimerized XXZ spin-$\frac{1}{2}$ chain with nearest-neighbor couplings which was studied numerically in Phys. Rev. B 106, L201106 (2022). The model has isotropic $XY$ couplings which have a uniform value…
Phase transitions of the mixed spin-1/2 and spin-S (S >= 1/2) Ising model on a three-dimensional (3D) decorated lattice with a layered magnetic structure are investigated within the framework of a precise mapping relationship to the simple…
We consider the competition of magnetic and charge ordering in high-Tc cuprates within the framework of the simplified static 2D spin-pseudospin model. This model is equivalent to the 2D dilute antiferromagnetic (AFM) Ising model with…