We report the realization of superconductivity by an isovalent doping with phosphorus in LaFeAsO. X-ray diffraction shows that, with the partial substitution of P for As, the Fe2As2 layers are squeezed while the La2O2 layers are stretched along the c-axis. Electrical resistance and magnetization measurements show emergence of bulk superconductivity at ∼10 K for the optimally-doped LaFeAs1−xPxO ...

– We compute the optical conductivity of 2D f-wave superconductors and also of the multigap model proposed recently by Zhitomirsky and Rice at T = 0K in the Born limit. The presence of interband impurity scattering was found to play an important role: the contributions from the two bands mix up, and new structures are seen in the tunneling density of states and in the optical spectrum as well, ...

Layered and pseudocubic Ru-based perovskites have been the subject of considerable recent attention, due to their unusual magnetic properties and the discovery of superconductivity in one member of the family, Sr2RuO4. From a magnetic point of view, interest derives from the stable ferromagnetism in SrRuO3, gradually disappearing to a non-magnetic phase upon substituting Sr with isovalent Ca, a...

We use first-principles calculations to extract two essential microscopic parameters, the charge-transfer energy and the inter-cell oxygen-oxygen hopping, which correlate with the maximum superconducting transition temperature Tc,max across the cuprates. We explore the superconducting state in the three-band model of the copper-oxygen planes using cluster Dynamical Mean-Field Theory. We find th...

We report ab initio quantum mechanical calculations of band structures of single-walled carbon nanotubes (SWNTs) using the B3LYP flavor of density functional theory. In particular, we find excellent agreement with the small band gaps in “metallic” zigzag SWNTs observed by Lieber et al. [0.079 vs 0.080 eV for (9,0), 0.041 vs 0.042 eV for (12,0), and 0.036 eV vs 0.029 eV for (15,0)]. This contras...

We report elastic neutron diffraction and muon spin relaxation (μSR) measurements of the quasi one-dimensional antiferromagnets Sr2CuO3 and Ca2CuO3, which have extraordinarily reduced TN/J ratios. We observe almost resolution-limited antiferromagnetic Bragg reflections in Sr2CuO3 and obtain a reduced ordered moment size of ∼0.06μB. We find that the ratio of ordered moment size μ(Ca2CuO3)/μ(Sr2C...

We use the Wilson-Fisher ǫ expansion to study quantum critical behavior in gauged Yukawa matrix field theories with weak quenched disorder. We find that the resulting quantum critical behavior is in the universality class of the pure system. As in the pure system, the phase transition is typically first order, except for a limited range of parameters where it can be second order with computable...

We present an analytical formula for the ratio of the physical spin correlation length of a two-dimensional Heisenberg antiferromagnet on a square lattice, and the one which is actually computed in numerical simulations. This latter correlation length is deduced from the second moment of the structure factor at the antiferromagnetic momentum Q. We show that the ratio is very close to one, in ag...

The dynamical stripe structure relating to the ”1/8 problem” was investigated in La2−xSrxCuO4 utilizing the high frequency response of Raman scattering. The split of the two-magnon peak due to the formation of the stripe structure was observed at whole Sr concentration region from x = 0.035 to 0.25 at low temperatures. Especially clear split was observed at low carrier concentration region x = ...

In analogy to the role of oxide anion in perovskites, halogen chemistry halide perovskites significantly contributes chemical, physical, and optoelectronic properties this class materials.Investigating manipulating site has improved our understanding electronic structure, reactivity, defect chemistry, ionic conductivity perovskites.A clear is expected (i) yield novel with targeted controlled (i...