272 research outputs found
Hierarchical structure formation in layered superconducting systems with multi-scale inter-vortex interactions
No full textWe demonstrate the formation of hierarchical structures in two-dimensional systems with multiple length scales in the inter-particle interaction. These include states such as clusters of clusters, concentric rings, clusters inside a ring, and stripes in a cluster. We propose to realize such systems in vortex matter (where a vortex is mapped onto a particle with multi-scale interactions) in layered superconducting systems with varying inter-layer thicknesses and different layer materials
Phase diagrams of vortex matter with multi-scale inter-vortex interactions in layered superconductors
No full textIt was recently proposed to use the stray magnetic fields of superconducting vortex lattices to trap ultracold atoms for building quantum emulators. This calls for new methods for engineering and manipulating of the vortex states. One of the possible routes utilizes type-1.5 superconducting layered systems with multi-scale inter-vortex interactions. In order to explore the possible vortex states that can be engineered, we present two phase diagrams of phenomenological vortex matter models with multi-scale inter-vortex interactions featuring several attractive and repulsive length scales. The phase diagrams exhibit a plethora of phases, including conventional 2D lattice phases, five stripe phases, dimer, trimer, and tetramer phases, void phases, and stable low-temperature disordered phases. The transitions between these states can be controlled by the value of an applied external field
Honeycomb, square, and kagome vortex lattices in superconducting systems with multiscale intervortex interactions
No full textThe recent proposal of Romero-Isart et al. [Phys. Rev. Lett. 111, 145304 (2013)] to utilize the vortex lattice phases of superconducting materials to prepare a lattice for ultracold-atom-based quantum emulators raises the need to create and control vortex lattices of different symmetries. Here we propose a mechanism by which honeycomb, hexagonal, square, and kagome vortex lattices could be created in superconducting systems with multiscale intervortex interactions. Multiple scales of the intervortex interaction can be created and controlled in layered systems made of different superconducting materials or with differing interlayer spacings
Special Issue on Solitons in Quantum Physics
No full textThis is an Editorial for the Special Issue on Solitons in Quantum Physics.</p
Replication Data for: LAWS IN CONFLICT: Legacies of War, Gender, and Legal Pluralism in Chechnya
No full textHow do legacies of conflict affect choices between state and nonstate legal institutions? This article studies this question in Chechnya, where state law coexists with Sharia and customary law. The author focuses on the effect of conflict-induced disruption of gender hierarchies, because nonstate legal orders are explicitly discriminatory against women. The author finds that women in Chechnya are more likely to rely on state law than men and that this gender gap in legal preferences and behavior is especially large in more-victimized communities. The author infers from this that the conflict created the conditions for women in Chechnya to pursue their interests through state law—albeit not without resistance. Women’s legal mobilization has generated a backlash from the Chechen government, which has attempted to reinstate a patriarchal order. The article concludes that such conflict may induce legal mobilization among the weak and that gender might become a central cleavage during state-building processes in postconflict environments
Replication Data for: LAWS IN CONFLICT: Legacies of War, Gender, and Legal Pluralism in Chechnya
No full textHow do legacies of conflict affect choices between state and nonstate legal institutions? This article studies this question in Chechnya, where state law coexists with Sharia and customary law. The author focuses on the effect of conflict-induced disruption of gender hierarchies, because nonstate legal orders are explicitly discriminatory against women. The author finds that women in Chechnya are more likely to rely on state law than men and that this gender gap in legal preferences and behavior is especially large in more-victimized communities. The author infers from this that the conflict created the conditions for women in Chechnya to pursue their interests through state law—albeit not without resistance. Women’s legal mobilization has generated a backlash from the Chechen government, which has attempted to reinstate a patriarchal order. The article concludes that such conflict may induce legal mobilization among the weak and that gender might become a central cleavage during state-building processes in postconflict environments
Superfluid States of Matter
No full textReview of Superfluid States of Matter by Boris Svistunov, Egor Babaev, and Nikolay Prokof ’ev, CRC Press, London, 2015, pp. xix + 561. Scope: monograph, £63.99, ISBN 978-1-4398-0275-5 (Hardcover). Level: postgraduates, research scientists
Non-Meissner electrodynamics and knotted solitons in two-component superconductors
No full textThis is the pre-published version harvested from arXiv. The published version is located at http://prb.aps.org/abstract/PRB/v79/i10/e104506I consider electrodynamics and the problem of knotted solitons in two-component superconductors. Possible existence of knotted solitons in multicomponent superconductors was predicted several years ago. However, their basic properties and stability in these systems remain an outstandingly difficult question both for analytical and numerical treatment. Here I propose a special perturbative approach to treat self-consistently all the degrees of freedom in the problem. I show that there exists a length scale for a Hopfion texture where the electrodynamics of a two-component superconductor is dominated by a self-induced Faddeev term, which is in stark contrast to the Meissner electrodynamics of single-component systems. I also show that at certain short length scales knotted solitons in the two-component Ginzburg-Landau model are not described by a Faddeev-Skyrme-type model and are unstable. However, these solitons can be stable at some intermediate length scales. I argue that configurations with high topological charge may be more stable in these systems than low-charge configurations. In the second part of the paper I discuss qualitatively different physics of the stability of knotted solitons in a more general Ginzburg-Landau model and point out the physically relevant terms which enhance or suppress the stability of knotted solitons. With this argument it is demonstrated that Ginzburg-Landau models possess stable knotted solitons
Unconventional Rotational Responses of Hadronic Superfluids in a Neutron Star Caused by Strong Entrainment and aΣ−Hyperon Gap
No full textThis is the pre-published version harvested from arXiv. The published version is located at http://prl.aps.org/abstract/PRL/v103/i23/e231101I show that the usual model of the rotational response of a neutron star, which predicts rotation-induced neutronic vortices and no rotation-induced protonic vortices, does not hold (i) beyond a certain threshold of entrainment interaction strength nor (ii) in the case of nonzero Σ- hyperon gap. I show that in both of these cases the rotational response involves the creation of phase windings in an electrically charged condensate. Lattices of bound states of vortices which result from these phase windings can (for a range of parameters) strongly reduce the interaction between rotation-induced vortices with magnetic-field carrying superconducting components
Topological defects in dirty two-band superconductors
No full textLAUREA MAGISTRALELa superconduttività a più componenti è un'estensione naturale della teoria convenzionale, nel caso il materiale abbia più di una banda superconduttrice. La facilità con cui si estende il modello tuttavia non rispecchia la moltitudine dei nuovi fenomeni. Questa tesi analizza alcuni di questi fenomeni, nel contesto di un modello Ginzburg-Landau a due bande microscopicamente derivato. In particolare questo modello ha un'interazione repulsiva come accoppiamento fra bande, e termini diffusivi interbanda dovuti ad impurità. Il modello cerca di descrivere alcune proprietà dei superconduttori a base di ferro, una nuova classe di superconduttori ad alta temperatura critica recentemente scoperti. Le impurità avranno un ruolo centrale, permettendo una transizione da uno stato s+- ad uno s++. Questa transizione può avvenire in modo discontinuo, producendo una nuovo tipo di vortice, il vortice a "fossato", oppure può avvenire in modo continuo, attraverso uno stato intermedio s+is. Quest'ultimo è un esempio di stato che rompe la simmetria rispetto all'inversione temporale (BTRS), impossibile da trovare in superconduttori convenzionali, e che presenta properietà magnetiche particolari, come la presenza di campi magnetici spontanei dentro il materiale, a differenza della classica elettrodinamica di London. Gli stati BTRS hanno anche effetti sull'interazione fra vortici, aprendo la possibilità alla superconduttività di tipo 1.5, un nuovo stato intermedio che involve la formazione di raggruppamenti di vortici. Oltre ai vortici, altri difetti topologici sono possibili, come gli Skyrmion e la pareti di dominio, che verranno studiati durante la tesi. Tutti i fenomeni sopracitati sono stati analizzati nel dettaglio all'interno del modello e simulati numericamente, attraverso il metodo degli elementi finiti.Multicomponent superconductivity arises as a natural extension of the conventional theory, when materials have more than one superconducting band. The triviality of the extension does not reflect at all the multitude of new possible exotic phenomena. The topic of this thesis is to analyze some of them, in the context of a microscopically derived Ginzburg-Landau two-band model. In particular the model studied has repulsive interband coupling interaction and interband impurity scattering. The model hopes to describe some of the physics of iron-based superconductors, a new class of high temperature superconductors recently discovered. The impurity will have a central role in the model, allowing transitions between gap states, from s+- to s++. This transition can happen abruptly with a crossover, producing a new form of vortex matter, the so called "moat-core" vortices or can happen smoothly through an intermediate s+is state. The latter is an example of broken time-reversal symmetry state (BTRS), impossible in conventional superconductivity, and presenting peculiar magnetic properties, like the appearance of spontaneous magnetic field inside the material, in contrast with the usual London electrodynamics. BTRS states also affects vortex interaction, opening the possibility of type-1.5 superconductivity, an intermediate new state involving vortex clusterization. Apart from vortex, other topological defects are possible in multicomponent systems, like Skyrmions and domain walls, that will be studied during the thesis. All the phenomena above mentioned have been extensively analyzed inside the model and numerically simulated, within a finite element framework
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