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...
Spin-wave velocities, density of magnetic excitations, and NMR relaxation in ferro-pnictides (2009)
Ong, Andrew, Uhrig, Goetz S., Sushkov, Oleg P.
We perform an analysis of the experimentally known temperature dependence of the staggered magnetization in the antiferromagnetic phase. This analysis allows us to put an upper limit on the unknown...
Pnictides as frustrated quantum antiferromagnet close to a quantum phase transition (2008)
Uhrig, Goetz S., Holt, Michael, Oitmaa, Jaan, Sushkov, Oleg P., Singh, Rajiv R. P.
We present a detailed description of the dynamics of the magnetic modes in the recently discovered superconducting pnictides using reliable self-consistent spin-wave theory and series expansion....
Milstein, Alexander I., Sushkov, Oleg P.
We consider the extended 2D $t-t'-t''-J$ model at zero temperature. Parameters of the model corresponds to doping by holes. Using the low doping effective action we demonstrate that the system can 1)...
Screening of Coulomb Impurities in Graphene (2007)
Terekhov, Ivan S., Milstein, Alexander I., Kotov, Valeri N., Sushkov, Oleg P.
We calculate exactly the vacuum polarization charge density in the field of a subcritical Coulomb impurity, $Z|e|/r$, in graphene. Our analysis is based on the exact electron Green's function,...
AC Hopping Magnetotransport Across the Spin Flop Transition in Lightly Doped La_2CuO_4 (2007)
Sushkov, Oleg P., Kotov, Valeri N.
The weak ferromagnetism present in insulating La_{2}CuO_4 at low doping leads to a spin flop transition, and to transverse (interplane) hopping of holes in a strong external magnetic field. This...
Luscher, Andreas, Milstein, Alexander I., Sushkov, Oleg P.
We derive the low-energy effective field theory of the extended t-J model in the regime of light doping. The action includes a previously unknown Berry phase term, which is discussed in detail. We...
Kotov, Valeri N., Sushkov, Oleg P., Neto, M. B. Silva, Benfatto, L., Neto, A. H. Castro
We show that, due to the weak ferromagnetism of La$_{2-x}$Sr$_x$CuO$_4$, an external magnetic field leads to a dimensional crossover 2D $\to$ 3D for the in-plane transport. The crossover results in...
Destruction of Neel order and local spin spirals in insulating La_{2-x}Sr_xCuO_4 (2006)
Luscher, Andreas, Milstein, Alexander I., Sushkov, Oleg P.
Starting from the t-J model, we derive an effective field theory describing the spin dynamics in the insulating phase of La_{2-x}Sr_xCuO_4, x < 0.055, at low temperature. Using Monte Carlo...
Spin-flop transitions and spin-wave gaps in La_2CuO_4 (2006)
Luscher, Andreas, Sushkov, Oleg P.
We study the spin-wave spectrum and the spin-flop transitions in La_2CuO_4 in a uniform magnetic field at zero temperature. Using the non-linear sigma-model, we show that a field applied along the...
Single-hole properties of the t-J model on the honeycomb lattice (2005)
Luscher, Andreas, Laeuchli, Andreas, Zheng, Weihong, Sushkov, Oleg P.
Motivated by the possible charge ordering in the recently discovered superconductor Na_xCoO_2 yH_2O, which at filling x=1/3 would correspond to a half-filled honeycomb lattice, we investigate the...
Local spin spirals in the Neel phase of La_{2-x}Sr_xCuO_4 (2005)
Luscher, Andreas, Misguich, Gregoire, Milstein, Alexander I., Sushkov, Oleg P.
Experimental observations of lightly doped La_{2-x}Sr_xCuO_4, x < 0.02, revealed remarkable magnetic properties such as the incommensurate noncollinear ordering (additional to the Neel ordering) and...
Spiral Spin Order and Transport Anisotropy in Underdoped Cuprates (2005)
Kotov, Valeri N., Sushkov, Oleg P.
We discuss the spiral spin density wave model and its application to explain properties of underdoped La$_{2-x}$Sr$_x$CuO$_4$. We argue that the spiral picture is theoretically well justified in the...
Kotov, Valeri N., Sushkov, Oleg P.
We study the in-plane resistivity anisotropy in the spin-glass phase of the high-$T_{c}$ cuprates, on the basis of holes moving in a spiral spin background. This picture follows from analysis of the...
Sushkov, Oleg P., Kotov, Valeri N.
The main feature in the elastic neutron scattering of La_{2-x}Sr_xCuO_4 is the existence of incommensurate peaks with positions that jump from 45 to 0 degrees at 5% doping. We show that the spiral...
Luscher, Andreas, Sushkov, Oleg P.
We consider a two-dimensional Heisenberg antiferromagnet on a square lattice with weakly coupled impurities, i.e. additional spins interacting with the host magnet by a small dimensionless coupling...
Stability of the spiral phase in the 2D extended t-J model (2004)
Kotov, Valeri N., Sushkov, Oleg P.
We analyze the t-t'-t''-J model at low doping by chiral perturbation theory and show that the (1,0) spiral state is stabilized by the presence of t',t'' above critical values around 0.2J, assuming...
Superconducting Spiral Phase in the two-dimensional t-J model (2003)
Sushkov, Oleg P., Kotov, Valeri N.
We analyse the t-t'-t''-J model, relevant to the superconducting cuprates. By using chiral perturbation theory we have determined the ground state to be a spiral for small doping \delta
Critical Dynamics of Singlet Excitations in a Frustrated Spin System (2000)
Kotov, Valeri N., Zhitomirsky, Michael E., Sushkov, Oleg P.
We construct and analyze a two-dimensional frustrated quantum spin model with plaquette order, in which the low-energy dynamics is controlled by spin singlets. At a critical value of frustration the...
Kotov, Valeri N., Sushkov, Oleg P.
We analyze the spectrum of the 2D S=1/2 frustrated Heisenberg model near the transition from the spontaneously dimerized spin-liquid phase into the Neel ordered phase. Two excitation branches: the...
Kotov, Valeri N., Oitmaa, J., Sushkov, Oleg P., Weihong, Zheng
We analyze the stability of the spontaneously dimerized spin-liquid phase of the frustrated Heisenberg antiferromagnet - the J1-J2 model. The lowest triplet excitation, corresponding to breaking of a...
One- and two-dimensional spin systems in the regime close to deconfinement of spinons (1999)
Byrnes, Tim M. R., Murphy, M. T., Sushkov, Oleg P.
Based on the Majumdar-Ghosh chain we construct several spin models which allow us to investigate spinon dynamics in the regime close to deconfinement of spinons. We consider the J1-J2-δ model,...
One- and two-dimensional spin systems in the regime close to deconfinement of spinons (1999)
Byrnes, Tim M. R., Murphy, M. T., Sushkov, Oleg P.
Based on the Majumdar-Ghosh chain we construct several spin models which allow us to investigate spinon dynamics in the regime close to deconfinement of spinons. We consider the J1-J2-δ model,...