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Extreme vortex pinning in the noncentrosymmetric superconductor CePt3Si
(2010)Physical Review BWe report on the vortex dynamics of a single crystal of the noncentrosymmetric heavy-fermion superconductor CePt3Si. Decays of the remnant magnetization display a logarithmic time dependence with rates that follow the temperature dependence expected from the Kim-Anderson theory. The creep rates are lower than observed in any other centrosymmetric superconductor and are not caused by high critical currents. On the contrary, the critical ...Journal Article -
Maintaining the duality of closeness and betweenness centrality
(2016)Social NetworksBetweenness centrality is generally regarded as a measure of others’ dependence on a given node, and therefore as a measure of potential control. Closeness centrality is usually interpreted either as a measure of access efficiency or of independence from potential control by intermediaries. Betweenness and closeness are commonly assumed to be related for two reasons: first, because of their conceptual duality with respect to dependency, ...Journal Article -
Asymmetric Relations in Longitudinal Social Networks
(2011)IEEE Transactions on Visualization and Computer GraphicsIn modeling and analysis of longitudinal social networks, visual exploration is used in particular to complement and inform other methods. The most common graphical representations for this purpose appear to be animations and small multiples of intermediate states, depending on the type of media available. We present an alternative approach based on matrix representation of gestaltlines (a combination of Tufte's sparklines with glyphs ...Journal Article -
Visualization Methods for Longitudinal Social Networks and Stochastic Actor-Oriented Modeling
(2012)Social NetworksAs a consequence of the rising interest in longitudinal social networks and their analysis, there is also an increasing demand for tools to visualize them. We argue that similar adaptations of state-of-the-art graph-drawing methods can be used to visualize both, longitudinal networks and predictions of stochastic actor-oriented models (SAOMs), the most prominent approach for analyzing such networks. The proposed methods are illustrated ...Journal Article -
Berezinskii-Kosterlitz-Thouless Paired Phase in Coupled XY Models
(2019)Physical Review LettersWe study the effect of a linear tunneling coupling between two-dimensional systems, each separately exhibiting the topological Berezinskii-Kosterlitz-Thouless (BKT) transition. In the uncoupled limit, there are two phases: one where the one-body correlation functions are algebraically decaying and the other with exponential decay. When the linear coupling is turned on, a third BKT-paired phase emerges, in which one-body correlations are ...Journal Article -
Anisotropic long-range spin systems
(2016)Physical Review BWe consider anisotropic long-range interacting spin systems in d dimensions. The interaction between the spins decays with the distance as a power law with different exponents in different directions: We consider an exponent d₁ + σ₁ in d₁ directions and another exponent d₂ + σ₂ in the remaining d₂ ≡ d − d₁ ones. We introduce a low energy effective action with nonanalytic power of the momenta. As a function of the two exponents σ₁ and σ₂ ...Journal Article -
Berezinskii–Kosterlitz–Thouless transition and criticality of an elliptic deformation of the sine-Gordon model
(2019)Journal of Physics A: Mathematical and TheoreticalWe introduce and study the properties of a periodic model interpolating between the sine-and the sinh-Gordon theories in 1 + 1 dimensions. This model shows the peculiarities, due to the preservation of the functional form of their potential across RG flows, of the two limiting cases: the sine-Gordon, not having conventional order/magnetization at finite temperature, but exhibiting Berezinskii–Kosterlitz–Thouless (BKT) transition; and ...Journal Article -
Dynamical Critical Scaling of Long-Range Interacting Quantum Magnets
(2018)Physical Review LettersSlow quenches of the magnetic field across the paramagnetic-ferromagnetic phase transition of spin systems produce heat. In systems with short-range interactions the heat exhibits universal power-law scaling as a function of the quench rate, known as Kibble-Zurek scaling. In this work we analyze slow quenches of the magnetic field in the Lipkin-Meshkov-Glick (LMG) model, which describes fully connected quantum spins. We analytically ...Journal Article -
Criticality and phase diagram of quantum long-range O(N) models
(2017)Physical Review BSeveral recent experiments in atomic, molecular, and optical systems motivated a huge interest in the study of quantum long-range systems. Our goal in this paper is to present a general description of their critical behavior and phases, devising a treatment valid in d dimensions, with an exponent d + σ for the power-law decay of the couplings in the presence of an O(N) symmetry. By introducing a convenient ansatz for the effective action, ...Journal Article -
Critical exponents of O(N) models in fractional dimensions
(2015)Physical Review DWe compute critical exponents of O(N) models in fractional dimensions between d = 2 and 4, and for continuous values of the number of field components N, in this way completing the RG classification of universality classes for these models. These curves represent nonperturbative approximation to the exact results, they respect all the qualitative features expected from such quantities conciliating previously known perturbative results in ...Journal Article