Field-induced local moments around nonmagnetic impurities in metallic cuprates

We consider a defect in a strongly correlated host metal and discuss, within a slave boson mean field formalism for the $t-t'-J$ model, the formation of an induced paramagnetic moment which is extended over nearby sites. We study in particular an impurity in a metallic band, suitable for modelling the optimally doped cuprates, in a regime where the impurity moment is paramagnetic. The form of the local susceptibility as a function of temperature and doping is found to agree well with recent NMR experiments, without including screening processes leading to the Kondo effect.Comment: 7 pages, submitted to Phys Rev

Helium condensation in aerogel: avalanches and disorder-induced phase transition

We present a detailed numerical study of the elementary condensation events (avalanches) associated to the adsorption of $^4$He in silica aerogels. We use a coarse-grained lattice-gas description and determine the nonequilibrium behavior of the adsorbed gas within a local mean-field analysis, neglecting thermal fluctuations and activated processes. We investigate the statistical properties of the avalanches, such as their number, size and shape along the adsorption isotherms as a function of gel porosity, temperature, and chemical potential. Our calculations predict the existence of a line of critical points in the temperature-porosity diagram where the avalanche size distribution displays a power-law behavior and the adsorption isotherms have a universal scaling form. The estimated critical exponents seem compatible with those of the field-driven Random Field Ising Model at zero temperature.Comment: 16 pages, 14 figure

Dimensions of dynamic marketing capability and export performance

Purpose The purpose of this paper is to develop a conceptual framework on the dimensions of dynamic marketing capability (DMC) and its relationship with export performance. The paper also proposes the mediating role of competitive hybrid strategy and the moderating role of environmental responsiveness in explaining the relationship between DMC and export performance. Design/methodology/approach By following the dynamic capability notion of the marketing and competitive strategy literature, this paper proposes a novel conceptualization of the DMC development process and the possible effect of DMC on attaining competitive advantage. Findings The paper postulates that a firm’s DMC can reflect complementary power when its higher-level marketing capabilities are bundled together to detect distributing channel members’ crucial needs, competitors’ action plans and satisfying market demand. As yet little is known about the main underlying dimensions of higher-level DMC construct, the paper contributes in proposing the key dimensions of DMC. Originality/value This research advances the knowledge-based view and resource-based views and evolves a solid foundation of DMC constructs comprising four higher-order marketing capabilities, namely, ambidextrous market orientation, customer relationship management capability, brand management capability and new product development capability. Thus, this paper contributes in DMC literature in explaining export performance

Normal State Magnetic Properties of Ni and Zn Substituted in YBa_{2}Cu_{3} O_{6+x}: Hole-Doping Dependence

We present SQUID susceptibility data on Zn and Ni substituted YBa_{2}Cu_{3}O_{6+x}. Cross-checks with NMR yield an unprecedented accuracy in the estimate of the magnetic susceptibility associated with the substituants, from the underdoped to the lightly overdoped case. This allows us to determine the Weiss temperature \theta for YBCO: its value is very small for all hole dopings n_h. Since in conventional metals, the Kondo temperature, $T_{K}<\theta$, magnetic screening effects would not be expected for $T\gg \theta$; in contrast, increasing n_h produces a reduction of the small moment induced by Zn^{2+} and a nearly constant effective moment for Ni^{2+} corresponding to a spin 1/2 rather than to a spin 1.Comment: 4 pages, 5 figures, to be published in Europhysics Letter

Bimodal Phase Diagram of the Superfluid Density in LaAlO3/SrTiO3 Revealed by an Interfacial Waveguide Resonator

We explore the superconducting phase diagram of the two-dimensional electron system at the LaAlO3/SrTiO3 interface by monitoring the frequencies of the cavity modes of a coplanar waveguide resonator fabricated in the interface itself. We determine the phase diagram of the superconducting transition as a function of temperature and electrostatic gating, finding that both the superfluid density and the transition temperature follow a dome shape, but that the two are not monotonically related. The ground state of this 2DES is interpreted as a Josephson junction array, where a transition from long- to short-range order occurs as a function of the electronic doping. The synergy between correlated oxides and superconducting circuits is revealed to be a promising route to investigate these exotic compounds, complementary to standard magneto-transport measurements.Comment: 5 pages, 4 figures and 10 pages of supplementary materia

Smecticlike phase for modulated XY spins in two dimensions

The row model for frustrated XY spins on a triangular lattice in 2D is used to study incommensurate{IC}) spiral and commensurate{C} antiferromagnetic (AF) phases, in the regime where a C-IC transition occurs. Using fluctuating boundary conditions and specific histogram techniques, a detailed Monte Carlo (MC) study reveals more structure in the phase diagram than found in previous MC simulations of the full parameter space. On the (C) side, equilibrium configurations consist of alternating stripes of spiral phases of opposite chirality separated by walls of the (C) phase. For this same parameter regime, thermodynamic quantities are computed analytically using the NSCHA, a generalization of the self consistent harmonic approximation appropriate for chiral systems. On the commensurate side of the (C)-(IC) boundary, NSCHA predicts an instability of the (C) phase. This suggests that the state is spatially inhomogeneous, consistent with the present MC result: it resembles the smectic-A phase of liquid crystals, and its existence implies that the Lifshitz point is at ${T=0}$ for modulated XY spins in 2D. The connection between frustrated XY systems and the vortex state of strong type II superconductors suggests that the smectic phase may correspond to a vortex liquid phase of superconducting layers.Comment: Single Postscript file containing 24 pages of text and 8 figures. To appear in May 1 issue of Phys. Rev. B, Vol. 5

Selforganized 3-band structure of the doped fermionic Ising spin glass

The fermionic Ising spin glass is analyzed for arbitrary filling and for all temperatures. A selforganized 3-band structure of the model is obtained in the magnetically ordered phase. Deviation from half filling generates a central nonmagnetic band, which becomes sharply separated at T=0 by (pseudo)gaps from upper and lower magnetic bands. Replica symmetry breaking effects are derived for several observables and correlations. They determine the shape of the 3-band DoS, and, for given chemical potential, influence the fermion filling strongly in the low temperature regime.Comment: 13 page