Related papers: Low-lying excitations in superconducting bilayer s…
Geometric frustration among competing spin exchanges can give rise to novel quantum phases by enhancing fluctuations that drive magnetic systems beyond the classical regime. We investigate the frustrated array of strongly correlated spin…
We discuss an experiment in which two magnetic insulators that both show a field-induced magnetic-ordering transition are weakly coupled to one another and are placed into an ex- ternal magnetic field. If the respective magnetic states can…
Pairing interaction between fermionic particles leads to composite Bosons that condense at low temperature. Such condensate gives rise to long range order and phase coherence in superconductivity, superfluidity, and other exotic states of…
The long-range spin-triplet supercurrent transport is an interesting phenomenon in the superconductor/ferromagnet ($S/F$) heterostructure containing noncollinear magnetic domains. Here we study the long-range superharmonic Josephson current…
We present our preliminary studies of an effective model of a superconductor with short coherence length involving magnetic interactions. The Hamiltonian considered consists of (i) the effective on-site interaction U, (ii) the intersite…
The Laughlin state embodies a universal class of fractional quantum Hall effects arising in two-dimensional electron systems subjected to strong perpendicular magnetic fields. Conventionally described by a single-component wavefunction, the…
Exact calculations of collective excitations and charge/spin (pseudo)gaps in an ensemble of bipartite and nonbipartite clusters yield level crossing degeneracies, spin-charge separation, condensation and recombination of electron charge and…
Fluxons in a superconducting loop can be coherently coupled by quantum phase slips occurring at a weak link such as a Josephson junction. If Cooper pair tunneling at the junction occurs through a resonant level, $2\pi$ quantum phase slips…
Excitons, the bosonic quasiparticle emerging from Coulomb interaction between electrons and holes, will undergo a Bose-Einstein condensation(BEC) and transition into a superfluid state with global phase coherence at low temperatures. An…
The stability of high vs. low spin states of transition metal complexes has been interpreted by ligand field theory, which is a perturbation theory of the electron-electron interaction. The present first principles calculation of a series…
Electron density oscillations with acoustic dispersions and sustained at boundaries between different media provide information about surface and interface properties of hetero-structures. In ultra-thin metallic films these plasmonic…
In this work we characterize the unusual nonlinear dynamics of the resonance response, exhibited by our NbN superconducting microwave resonators, using different operating conditions. The nonlinear dynamics, occurring at relatively low…
The state with a spontaneous interlayer phase coherence in a graphene based bilayer quantum Hall system is studied. This state can be considered as a gas of superfluid electron-hole pairs with the components of the pair belonging to…
The angular momentum of an electron is characterized well by pseudospin with $J=3/2$ in the presence of strong spin-orbit interactions. We study theoretically the Josephson effect of superconductors in which such two $J=3/2$ electrons form…
The competition between tunneling and interactions in bosonic lattice models generates a whole variety of different quantum phases. While, in the presence of a single species interacting via on-site interaction, the phase diagram presents…
Independently exchange biased subsystems can coexist in FeF2/Ni bilayers after various field-cooling protocols. We find double hysteresis loops for intermediate cooling fields, while for small or large cooling fields a negatively or…
In a bilayer system of fermionic dipoles, a full control over the strength of the attractive interactions between two layers leads to the BCS-BEC crossover. Here, using the BCS mean field theory, we study such a crossover in symmetric…
The BCS theory has been extended by us to the strong-coupling regime where carriers are small lattice polarons and bipolarons. Here I review the multi-polaron strong-coupling theory of superconductivity. Attractive electron correlations,…
Bilayer graphene has two non-equivalent sublattices and, therefore, the same adatom impurity can manifest in spectrally distinct ways-sharp versus broad resonances near the charge neutrality-depending on the sublattice it adsorbs at.…
Magneto-luminescence studies in electron bilayers reveal the hallmarks of the even-denominator and other quantum Hall states in the intensities and energies of the inter-band optical recombination lines. In the presence of a small tunneling…