Coulomb Disorder Effects on ARPES and NQR Spectra in Cuprates (2009)
Chen, Wei, Khaliullin, Giniyat, Sushkov, Oleg P.
The role of Coulomb disorder, either of extrinsic origin or introduced by dopant ions in undoped and lightly-doped cuprates, is studied. We demonstrate that charged surface defects in an insulator...
Magnetically Hidden Order of Kramers Doublets in $d^1$ Systems: Sr$_2$VO$_4$ (2009)
Jackeli, George, Khaliullin, Giniyat
We formulate and study an effective Hamiltonian for low-energy Kramers doublets of $d^1$-ions on a square lattice. We find that the system exhibits a magnetically hidden order in which the...
Evolution of Spin-Orbital-Lattice Coupling in the $R$VO$_3$ Perovskites (2008)
Horsch, Peter, Oles', Andrzej M., Feiner, Louis Felix, Khaliullin, Giniyat
We introduce a microscopic model which unravels the physical mechanisms responsible for the observed phase diagram of the $R$VO$_3$ perovskites. It reveals a nontrivial interplay between...
One-dimensional orbital fluctuations and the exotic magnetic properties of YVO$_3$ (2007)
Oles, Andrzej M., Horsch, Peter, Khaliullin, Giniyat
Starting from the Mott insulator picture for cubic vanadates, we derive and investigate the model of superexchange interactions between V$^{3+}$ ions, with nearly degenerate $t_{2g}$ orbitals...
Spin-orbital entanglement near quantum phase transitions (2007)
Oles, Andrzej M., Horsch, Peter, Khaliullin, Giniyat
Spin-orbital entanglement in the ground state of a one-dimensional SU(2)$\otimes$SU(2) spin-orbital model is analyzed using exact diagonalization of finite chains. For $S=1/2$ spins and $T=1/2$...
Spin-Orbital Entanglement and Violation of the Goodenough-Kanamori Rules (2006)
Oles, Andrzej M., Horsch, Peter, Feiner, Louis Felix, Khaliullin, Giniyat
We point out that large composite spin-orbital fluctuations in Mott insulators with $t_{2g}$ orbital degeneracy are a manifestation of quantum entanglement of spin and orbital variables. This results...
Oles, Andrzej M., Khaliullin, Giniyat, Horsch, Peter, Feiner, Louis Felix
The temperature dependence and anisotropy of optical spectral weights associated with different multiplet transitions is determined by the spin and orbital correlations. To provide a systematic basis...
Orbital order and fluctuations in Mott insulators (2005)
Basic mechanisms controlling orbital order and orbital fluctuations in transition metal oxides are discussed. The lattice driven classical orbital picture, e.g. like in manganites LaMnO$_3$, is...
Doping dependence of density response and bond-stretching phonons in cuprates (2005)
Horsch, Peter, Khaliullin, Giniyat
We explain the anomalous doping dependence of zone boundary $(\pi,0)$ and $(\pi,\pi)$ bond-stretching phonons in the high-temperature superconductor La$_{2-\delta}$Sr$_{\delta}$CuO$_4$ in the doping...
Theory of optical spectral weights in Mott insulators with orbital degrees of freedom (2004)
Khaliullin, Giniyat, Horsch, Peter, Oles, Andrzej M.
Introducing partial sum rules for the optical multiplet transitions, we outline a unified approach to magnetic and optical properties of strongly correlated transition metal oxides. On the example of...
Miyashita, Satoshi, Kawaguchi, Akira, Kawakami, Norio, Khaliullin, Giniyat
We investigate ground-state properties and quantum phase transitions in the one-dimensional S=1 spin-orbital model relevant to cubic vanadates. Using the density matrix renormalization group, we...
Dimerization versus Orbital Moment Ordering in the Mott insulator YVO$_3$ (2003)
Horsch, Peter, Khaliullin, Giniyat, Oles, Andrzej M.
We use exact diagonalization combined with mean-field theory to investigate the phase diagram of the spin-orbital model for cubic vanadates. The spin-orbit coupling competes with Hund's exchange and...
Quantum behavior of Orbitals in Ferromagnetic Titanates: Novel Orderings and Excitations (2002)
Khaliullin, Giniyat, Okamoto, Satoshi
We investigate the collective behavior of orbital angular momentum in the spin ferromagnetic state of a Mott insulator with $t_{2g}$ orbital degeneracy. The frustrated nature of the interactions...
Orbital effects in manganites (2002)
Brink, Jeroen Van Den, Khaliullin, Giniyat, Khomskii, Daniel
We review some aspects related to orbital degrees of freedom in manganites. The Mn$^{3+}$ ions in these compounds have double orbital degeneracy and are strong Jahn-Teller ions, causing structural...
Coulomb interaction and stability of CE-type structure in half-doped manganites, reply (2001)
Brink, Jeroen Van Den, Khaliullin, Giniyat, Khomskii, Daniel
In his Comment (cond-mat/0104353), Shen points out that the on-site Coulomb interaction, that can cause charge order in half-doped manganites, also destabilizes the magnetic CE-phase observed in...
Charge and orbital order in half-doped manganites (1999)
Brink, Jeroen Van Den, Khaliullin, Giniyat, Khomskii, Daniel
An explanation is given for the charge order, orbital order and insulating state observed in half-doped manganese oxides, such as Nd$_{1/2}$Sr$_{1/2}$MnO$_{3}$. The competition between the kinetic...