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Full-Text Articles in Physics
Fluctuation-Induced First Order Phase Transitions In Type-1.5 Superconductors In Zero External Field, Hannes Meier, Egor Babaev, Mats Wallin
Fluctuation-Induced First Order Phase Transitions In Type-1.5 Superconductors In Zero External Field, Hannes Meier, Egor Babaev, Mats Wallin
Egor Babaev
No abstract provided.
Vortex Chains Due To Nonpairwise Interactions And Field-Induced Phase Transitions Between States With Different Broken Symmetry In Superconductors With Competing Order Parameters, Julien Garaud, Egor Babaev
Vortex Chains Due To Nonpairwise Interactions And Field-Induced Phase Transitions Between States With Different Broken Symmetry In Superconductors With Competing Order Parameters, Julien Garaud, Egor Babaev
Egor Babaev
We study superconductors with two order components and phase separation driven by intercomponent density-density interaction, focusing on the phase where only one condensate has nonzero ground-state density and a competing order parameter exists only in vortex cores. We demonstrate there that multibody intervortex interactions can be strongly nonpairwise, leading to some unusual vortex patterns in an external field, such as vortex pairs and vortex chains. We demonstrate that in an external magnetic field such a system undergoes a field-driven phase transition from (broken) U(1) to (broken) U(1)×U(1) symmetries when a subdominant order parameter in the vortex cores acquires global coherence. …
Spontaneous Breakdown Of Time-Reversal Symmetry Induced By Thermal Fluctuations, Johan Carlström, Egor Babaev
Spontaneous Breakdown Of Time-Reversal Symmetry Induced By Thermal Fluctuations, Johan Carlström, Egor Babaev
Egor Babaev
In systems with broken U(1) symmetry, such as superfluids, superconductors or magnets, the symmetry restoration is driven by proliferation of topological defects in the form of vortex loops. Here we discuss that in certain systems the proliferation of topological defects can, by contrast, lead to the breakdown of an additional symmetry. As a particular example we demonstrate that this effect should take place in s + is superconductors, which are widely discussed in connection with the Iron-based materials. In these systems a vortex excitation can create a “bubble" of fluctuating Z2 order parameter. Thermal excitation of vortices then leads to …
Entropy- And Flow- Induced Superfluid States, Johan Carlström, Egor Babaev
Entropy- And Flow- Induced Superfluid States, Johan Carlström, Egor Babaev
Egor Babaev
No abstract provided.
Domain Walls And Their Experimental Signatures In S + Is Superconductors, Julien Garaud, Egor Babaev
Domain Walls And Their Experimental Signatures In S + Is Superconductors, Julien Garaud, Egor Babaev
Egor Babaev
No abstract provided.
Honeycomb, Square, And Kagome Vortex Lattices In Superconducting Systems With Multi-Scale Inter-Vortex Interactions, Qingyou Meng, Christopher N. Varney, Hans Fangohr, Egor Babaev
Honeycomb, Square, And Kagome Vortex Lattices In Superconducting Systems With Multi-Scale Inter-Vortex Interactions, Qingyou Meng, Christopher N. Varney, Hans Fangohr, Egor Babaev
Egor Babaev
The recent proposal of Romero-Isart et al. [1] to utilize the vortex lattice phases of superconducting materials to prepare a lattice for ultra-cold atoms-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 multi-scale inter-vortex interaction. Multiple scales of the inter-vortex interaction can be created and controlled in layered systems made of different superconducting material or with differing interlayer spacing.
Muon-Spin Rotation Measurements Of The Vortex State In Sr2ruo4: Type-1.5 Superconductivity, Vortex Clustering And A Crossover From A Triangular To A Square Vortex Lattice, S.J. Ray, A.S. Gibbs, S.J. Bending, P.J. Curran, Egor Babaev, C. Baines, A.P. Mackenzie, S.L. Lee
Muon-Spin Rotation Measurements Of The Vortex State In Sr2ruo4: Type-1.5 Superconductivity, Vortex Clustering And A Crossover From A Triangular To A Square Vortex Lattice, S.J. Ray, A.S. Gibbs, S.J. Bending, P.J. Curran, Egor Babaev, C. Baines, A.P. Mackenzie, S.L. Lee
Egor Babaev
Muon-spin rotation has been used to probe the vortex state in Sr2RuO4. At moderate fields and temperatures a lattice of triangular symmetry is observed, crossing over to a lattice of square symmetry with increasing field and temperature. At lower fields it is found that there are large regions of the sample that are completely free from vortices which grow in volume as the temperature falls. Importantly this is accompanied by increasing vortex density and increasing disorder within the vortex-cluster-containing regions. Both effects are expected to result from the strongly temperature-dependent long-range vortex attractive forces arising from the multiband chiral-order superconductivity.
Skyrmions Induced By Dissipationless Drag In U(1) U (1) Superconductors, Julien Garaud, Karl A. H. Sellin, Juha JAykk, Egor Babaev
Skyrmions Induced By Dissipationless Drag In U(1) U (1) Superconductors, Julien Garaud, Karl A. H. Sellin, Juha JAykk, Egor Babaev
Egor Babaev
Rather generically, multicomponent superconductors and superfluids have intercomponent current-current interaction. We show that in superconductors with substantially strong intercomponent drag interaction, the topological defects which form in an external field are characterized by a skyrmionic topological charge. We then demonstrate that they can be distinguished from ordinary vortex matter by a very characteristic magnetization process due to the dipolar nature of inter-skyrmion forces. The results provide an experimental signature to confirm or rule out the formation p-wave state with reduced spin stiffness in p-wave superconductors.
Microscopic Prediction Of Skyrmion Lattice State In Clean Interface Superconductors, Daniel F. Agterberg, Egor Babaev, Julien Garaud
Microscopic Prediction Of Skyrmion Lattice State In Clean Interface Superconductors, Daniel F. Agterberg, Egor Babaev, Julien Garaud
Egor Babaev
When an in-plane field is applied to a clean interface superconductor, a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)-like phase is stabilized. This phase has a U(1)×U(1) symmetry and, in principle, this symmetry allows for flux carrying topological excitations different from Abrikosov vortices (which are the simplest defects associated with S1 → S1 maps). However, in practice, largely due to electromagnetic and other intercomponent interactions, such topological excitations are very rare in superconducting systems. Here, we demonstrate that a realistic microscopic theory for interface superconductors, such as SrTiO3/LaAlO3, predicts an unconventional magnetic response where the flux-carrying objects are skyrmions, characterized by homotopy invariants of S2 …
Topological Defects In Mixtures Of Superconducting Condensates With Different Charges, Julien Garaud, Egor Babaev
Topological Defects In Mixtures Of Superconducting Condensates With Different Charges, Julien Garaud, Egor Babaev
Egor Babaev
We investigate the topological defects in phenomenological models describing mixtures of charged condensates with commensurate electric charges. Such situations are expected to appear for example in liquid metallic deuterium. This is modeled by a multicomponent Ginzburg-Landau theory where the condensates are coupled to the same gauge field by different coupling constants whose ratio is a rational number. We also briefly discuss the case where electric charges are incommensurate. Flux quantization and finiteness of the energy per unit length dictate that the different condensates have different winding and thus different number of (fractional) vortices. Competing attractive and repulsive interactions lead to …
Phase Transitions And Anomalous Normal State In Superconductors With Broken Time Reversal Symmetry, Troels Arnfred Bojesen, Egor Babaev, Asle Sudbo
Phase Transitions And Anomalous Normal State In Superconductors With Broken Time Reversal Symmetry, Troels Arnfred Bojesen, Egor Babaev, Asle Sudbo
Egor Babaev
No abstract provided.
Rotational Response Of Superconductors: Magneto-Rotational Isomorphism And Rotation-Induced Vortex Lattice, Egor Babaev, Boris Svistunov
Rotational Response Of Superconductors: Magneto-Rotational Isomorphism And Rotation-Induced Vortex Lattice, Egor Babaev, Boris Svistunov
Egor Babaev
The analysis of nonclassical rotational response of superfluids and superconductors was performed by Onsager [Onsager, Nuovo Cimento, Suppl. 6, 279 (1949)] and London [Superfluids(Wiley, New York, 1950)] and crucially advanced by Feynman [Prog. Low Temp. Phys. 1, 17 (1955)]. It was established that, in the thermodynamic limit, neutral superfluids rotate by forming—without any threshold—a vortex lattice. In contrast, the rotation of superconductors at angular frequency —supported by uniform magnetic field BL ∝ due to surface currents—is of the rigid-body type (London law). Here we show that, neglecting the centrifugal effects, the behavior of a rotating superconductor is identical to that …
Vortex Matter In U(1)×U(1)×Z2 Phase-Separated Superconducting Condensates, Julien Garaud, Egor Babaev
Vortex Matter In U(1)×U(1)×Z2 Phase-Separated Superconducting Condensates, Julien Garaud, Egor Babaev
Egor Babaev
We study the properties of vortex solutions and magnetic response of two-component U(1)×U(1)×Z2 superconductors, with phase separation driven by intercomponent density-density interaction. Such a theory can be viewed arising from the breakdown of SU(2) symmetry by a biquadratic interaction between the components of the field. Depending on the symmetry-breaking term, there are two ground-state phases: one where both components of the doublet are equal (the miscible phase) and one where only one component assumes a nonzero vacuum expectation value (the immiscible state). In the latter phase, the spectrum of topological excitations contains both domain walls and vortices. We show the …
Chiral Cp^2 Skyrmions In Three-Band Superconductors, Garaud Julien, Johan CarlstrOm, Egor Babaev, Martin Speight
Chiral Cp^2 Skyrmions In Three-Band Superconductors, Garaud Julien, Johan CarlstrOm, Egor Babaev, Martin Speight
Egor Babaev
No abstract provided.
Stripe, Gossamer, And Glassy Phases In Systems With Strong Non-Pairwise Interactions, Karl A. H. Sellin, Egor Babaev
Stripe, Gossamer, And Glassy Phases In Systems With Strong Non-Pairwise Interactions, Karl A. H. Sellin, Egor Babaev
Egor Babaev
We study structure formation in systems of classical particles in two dimensions with long-range attractive short-range repulsive two-body interactions and repulsive three-body interactions. Stripe, gossamer, and glass phases are found as a result of nonpairwise interaction.
Hierarchical Structure Formation In Layered Superconducting Systems With Multi-Scale Inter-Vortex Interactions, Christopher N. Varney, Karl A. H. Sellin, Qing-Ze Wang, Hans Fangohr, Egor Babaev
Hierarchical Structure Formation In Layered Superconducting Systems With Multi-Scale Inter-Vortex Interactions, Christopher N. Varney, Karl A. H. Sellin, Qing-Ze Wang, Hans Fangohr, Egor Babaev
Egor Babaev
We 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.
Freezing Of An Unconventional Two-Dimensional Plasma, Egil V. Herland, Egor Babaev, Parsa Bonderson, Victor Gurarie, Chetan Nayak, Leo Radzihovsky, Asle Sudbo
Freezing Of An Unconventional Two-Dimensional Plasma, Egil V. Herland, Egor Babaev, Parsa Bonderson, Victor Gurarie, Chetan Nayak, Leo Radzihovsky, Asle Sudbo
Egor Babaev
No abstract provided.
Classification Of Ground States And Normal Modes For Phase-Frustrated, Daniel Weston, Egor Babaev
Classification Of Ground States And Normal Modes For Phase-Frustrated, Daniel Weston, Egor Babaev
Egor Babaev
No abstract provided.
Phase Structure And Phase Transitions In A Three Dimensional Su(2) Superconductor, Egil V. Herland, Troels A. Bojesen, Egor Babaev, Asle Sudb
Phase Structure And Phase Transitions In A Three Dimensional Su(2) Superconductor, Egil V. Herland, Troels A. Bojesen, Egor Babaev, Asle Sudb
Egor Babaev
No abstract provided.
Time Reversal Symmetry Breakdown In Normal And Superconducting States In Frustrated Three-Band Systems, Troels Arnfred Bojesen, Egor Babaev, Asle Sudbo
Time Reversal Symmetry Breakdown In Normal And Superconducting States In Frustrated Three-Band Systems, Troels Arnfred Bojesen, Egor Babaev, Asle Sudbo
Egor Babaev
We discuss the phase diagram and phase transitions in U(1)×Z2 three-band superconductors with broken time reversal symmetry. We find that beyond mean-field approximation and for sufficiently strong frustration of interband interactions there appears an unusual metallic state precursory to a superconducting phase transition. In that state, the system is not superconducting. Nonetheless, it features a spontaneously broken Z2 time reversal symmetry. By contrast, for weak frustration of interband coupling the energy of a domain wall between different Z2 states is low and thus fluctuations restore broken time reversal symmetry in the superconducting state at low temperatures.
Unusual Mechanism Of Vortex Viscosity Generated By Mixed Normal Modes In Superconductors With Broken Time Reversal Symmetry, Mihail Silaev, Egor Babaev
Unusual Mechanism Of Vortex Viscosity Generated By Mixed Normal Modes In Superconductors With Broken Time Reversal Symmetry, Mihail Silaev, Egor Babaev
Egor Babaev
We show that under certain conditions, multiband superconductors with broken time reversal symmetry have a vortex viscosity-generating mechanism which is different from that in conventional superconductors. It appears due to the existence of a mixed superfluid phase-density mode inside the vortex core. This contribution is dominant near the time reversal symmetry-breaking phase transition. The results could be relevant for the three-band superconductor Ba1−xKxFe2As2.
Skyrmionic State And Stable Half-Quantum Vortices In Chiral P-Wave Superconductors, Julien Garaud, Egor Babaev
Skyrmionic State And Stable Half-Quantum Vortices In Chiral P-Wave Superconductors, Julien Garaud, Egor Babaev
Egor Babaev
Observability of half-quantum vortices and skyrmions in p-wave superconductors is an outstanding open question. Under the most common conditions, fractional flux vortices are not thermodynamically stable in bulk samples. Here we show that in chiral p-wave superconductors, there is a regime where, in contrast lattices of integer flux vortices are not thermodynamically stable. Instead skyrmions made of spatially separated half-quantum vortices are the topological defects produced by an applied external field.
Vortex Coalescence And Type-1.5 Superconductivity In Sr2ruo4, Egor Babaev
Vortex Coalescence And Type-1.5 Superconductivity In Sr2ruo4, Egor Babaev
Egor Babaev
Recently vortex coalescence was reported in superconducting Sr2RuO4 by several experimental groups for fields applied along the c axis. We argue that Sr2RuO4 is a type-1.5 superconductor with long-range attractive, short-range repulsive intervortex interaction. The type-1.5 behavior stems from an interplay of the two orbital degrees of freedom describing this chiral superconductor together with the multiband nature of the superconductivity. These multiple degrees of freedom give rise to multiple coherence lengths, some larger and some smaller than the magnetic field penetration length, resulting in nonmonotonic intervortex forces.
Screening Properties And Phase Transitions In Unconventional Plasmas For Ising-Type Quantum Hall States, Egil Herland, Egor Babaev, Parsa Bonderson, Victor Gurarie, Chetan Nayak, Asle Sudbø
Screening Properties And Phase Transitions In Unconventional Plasmas For Ising-Type Quantum Hall States, Egil Herland, Egor Babaev, Parsa Bonderson, Victor Gurarie, Chetan Nayak, Asle Sudbø
Egor Babaev
Utilizing large-scale Monte-Carlo simulations, we investigate an unconventional two-component classical plasma in two dimensions which controls the behavior of the norms and overlaps of the quantum-mechanical wavefunctions of Ising-type quantum Hall states. The plasma differs fundamentally from that which is associated with the two-dimensional XY model and Abelian fractional quantum Hall states. We find that this unconventional plasma undergoes a Berezinskii-Kosterlitz-Thouless phase transition from an insulator to a metal. The parameter values corresponding to Ising-type quantum Hall states lie on the metallic side of this transition. This result verifies the required properties of the unconventional plasma used to demonstrate that …
Microscopic Derivation Of Two-Component Ginzburg-Landau Model And Conditions Of Its Applicability In Two-Band Systems, Mihail Silaev, Egor Babaev
Microscopic Derivation Of Two-Component Ginzburg-Landau Model And Conditions Of Its Applicability In Two-Band Systems, Mihail Silaev, Egor Babaev
Egor Babaev
We report a microscopic derivation of two-component Ginzburg-Landau (GL) field theory and the conditions of its validity in two-band superconductors. We also investigate the conditions when microscopically derived or phenomenological GL models fail and one should resort to a microscopic description. We show that besides being directly applicable at elevated temperatures, a version of a minimal two-component GL theory in certain cases also gives accurate description of certain aspects of a two-band system even substantially far from $T_c$. This shows that two-component GL model can be used for addressing a wide range of questions in multiband systems, in particular vortex …
Length Scales, Collective Modes, And Type-1.5 Regimes In Three-Band Superconductors, Johan Carlstrom, Julien Garaud, Egor Babaev
Length Scales, Collective Modes, And Type-1.5 Regimes In Three-Band Superconductors, Johan Carlstrom, Julien Garaud, Egor Babaev
Egor Babaev
The recent discovery of iron pnictide superconductors has resulted in a rapidly growing interest in multiband models with more than two bands. In this work we specifically focus on the properties of three-band Ginzburg-Landau models which do not have direct counterparts in more studied two-band models. First we derive normal modes and characteristic length scales in the conventional U(1) three-band Ginzburg-Landau model as well as in its time reversal symmetry broken counterpart with $U(1)\times Z_2$ symmetry. We show that in the latter case, the normal modes are mixed phase/density collective excitations. A possibility of the appearance of a massless phase-difference …
Topological Solitons In Three-Band Superconductors With Broken Time Reversal Symmetry, Julien Garaud, Johan Carlstrom, Egor Babaev
Topological Solitons In Three-Band Superconductors With Broken Time Reversal Symmetry, Julien Garaud, Johan Carlstrom, Egor Babaev
Egor Babaev
We show that three-band superconductors with broken time reversal symmetry allow magnetic flux-carrying stable topological solitons which have only a slightly higher energy than ordinary vortices. Therefore they can be induced by fluctuations or quenching the system through a phase transition. It can provide an experimental signature of the time reversal symmetry breakdown.
Comment On Phys. Rev. B 83, 054515 (2011) By V. G. Kogan And J. Schmalian And Comment On Their Reply Phys. Rev. B 86, 016502 (2012), Egor Babaev, Mihail Silaev
Comment On Phys. Rev. B 83, 054515 (2011) By V. G. Kogan And J. Schmalian And Comment On Their Reply Phys. Rev. B 86, 016502 (2012), Egor Babaev, Mihail Silaev
Egor Babaev
The recent paper by V. G. Kogan and J. Schmalian Phys. Rev. B 83, 054515 (2011) argues that the widely used two-component Ginzburg-Landau (GL) models are not correct, and further concludes that in the regime which is described by a GL theory there could be no disparity in the coherence lengths of two superconducting components. This would in particular imply that (in contrast to $U(1)\times U(1)$ superconductors), there could be no "type-1.5" superconducting regime in U(1) multiband systems for any finite interband coupling strength. We point out that these claims are incorrect and based on an erroneous scheme of reduction …
Microscopic Theory Of Type-1.5 Superconductivity In Multiband Systems, Mihail Silaev, Egor Babaev
Microscopic Theory Of Type-1.5 Superconductivity In Multiband Systems, Mihail Silaev, Egor Babaev
Egor Babaev
We report a self-consistent microscopic theory of characteristic length scales, vortex structure and type-1.5 superconducting state in two-band systems using two-band Eilenberger formalism.
Type-1.5 Superconducting State From An Intrinsic Proximity Effect In Two-Band Superconductors, Egor Babaev, Johan Carlstrom, Martin Speight
Type-1.5 Superconducting State From An Intrinsic Proximity Effect In Two-Band Superconductors, Egor Babaev, Johan Carlstrom, Martin Speight
Egor Babaev
We show that in multiband superconductors, even an extremely small interband proximity effect can lead to a qualitative change in the interaction potential between superconducting vortices by producing long-range intervortex attraction. This type of vortex interaction results in an unusual response to low magnetic fields leading to phase separation into domains of two-component Meissner states and vortex droplets.