Band calculations for supercells of La((2-x))Ba(x)CuO(4) show that the rigid band model for doping is less adequate than what is commonly assumed. In particular, weak ferromagnetism can appear locally around clusters of high Ba concentration. The clustering is important at large dilution, and averaged models for magnetism, such as the virtual crystal approximation, are unable to stabilize magne...

Here we correct, extend, and clarify results concerning the spin Hamiltonian HS used to describe the ground manifold of Hubbard models for magnetic insulators in the presence of spin-orbit interactions. Most of our explicit results are for a tetragonal lattice as applied to some of the copper oxide lamellar systems and are obtained within the approximation that HS consists of a sum of nearest-n...

We report a La2CuO4-like interlayer antiferromagnetic order in Sr2IrO4 films with large orthorhombic distortion (> 1.5%). The biaxial lattice strain epitaxial heterostructures of Sr2IrO4/Ca3Ru2O7 lowers the crystal symmetry from tetragonal (C4) to (C2), guiding Ir 5d Jeff = 1/2 pseudospin moment parallel elongated b-axis via magnetic anisotropy. From resonant X-ray scattering experiments, we ob...

Using high temperature expansions for the equal time correlator S(q) and static susceptibility χ(q) for the t-J model, we present evidence for quantum critical (QC), z=1, behavior at intermediate temperatures in a broad range of t/J ratio, doping, and temperatures. We find that the dynamical susceptibility is very close to the universal scaling function computable for the asymptotic QC regime, ...

This work expands the results and derivations presented in a recent letter. It is argued that symmetry breaking Hartree-Fock (HF) solutions of a simple model of the Cu-O planes in La2CuO4, are able to describe the insulator and antiferromagnetic characters of this material. Then, this classical primer of a Mott insulator is alternatively obtained here as an exact Slater insulator within the sim...

We calculate the antiferromagnetic spin wave dispersion in the half-filled (electronic density n = 1) Hubbard model for a two-dimensional square lattice, using the random phase approximation (RPA) in a broken symmetry (spin density wave) ground state. Our results for the spin wave dispersion, ω(q), are compared with high-resolution inelastic neutron scattering performed on La 2 CuO 4. The effec...

Filomena Forte,1,2 Luuk J. P. Ament,1 and Jeroen van den Brink1,3 1Institute-Lorentz for Theoretical Physics, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands 2Dipartimento di Fisica “E. R. Caianiello,” Università di Salerno, I-84081 Baronissi, Salerno, Italy and Laboratorio Regionale SuperMat, INFM-CNR, I-84081 Baronissi, Salerno, Italy 3Institute for Molecules and Materials...

To leading order in displacement size, the scattering of electrons in a Cu-O plane from O displacements perpendicular to that plane is due to spin-orbit coupling. This scattering is investigated with the following results: (1) As a consequence of timereversal symmetry, spin fluctuations, which can strongly enhance scattering from a spin impurity, do not enhance spin-orbit scattering; and (2) fo...

The lightly doped La2CuO4 of the high temperature superconducting Cu oxides shows spin glass behavior at very low temperatures, which reflects the effects of quantum fluctuations and frustration upon doping. Recent neutron scattering experiments revealed a formation of spin stripes at the same low concentration of doping. A specific relation between the two important properties of spin glass be...