Boson-Fermion Duality and Metastability in Cuprate Superconductors

The intrinsic structural metastability in cuprate high T$_c$ materials, evidenced in a checker-board domain structure of the CuO$_2$ planes, locally breaks translational and rotational symmetry. Dynamical charge - deformation fluctuations of such nano-size unidirectional domains, involving Cu-O-Cu molecular bonds, result in resonantly fluctuating diamagnetic pairs embedded in a correlated Fermi liquid. As a consequence, the single-particle spectral properties acquire simultaneously (i) fermionic low energy Bogoliubov branches for propagating Cooper pairs and (ii) bosonic localized glassy structures for tightly bound states of them at high energies. The partial localization of the single-particle excitations results in a fractionation of the Fermi surface as the strength of the exchange coupling between itinerant fermions and partially localized fermion pairs increases upon moving from the nodal to the anti-nodal point. This is also the reason why, upon hole doping, bound fermion pairs predominantly accumulate near the anti-nodal points and ultimately condense in an anisotropic fashion, tracking the gap in the single particle spectrum.Comment: 11 pages 5figure

Bogoliubov shadow bands in the normal state of superconducting systems with strong pair fluctuations

On the basis of a scenario where electron pairing is induced by resonant two-particle scattering (the Boson Fermion model), we show how precursors of the superconducting state - in form of overdamped Bogoliubov modes - emerge in the normal state upon approaching the transition temperature from above. This result is obtained by a renormalization technique based on continuous unitary transformations (the flow equations), projecting out the coherent contributions in the electron spectral function from an incoherent background.Comment: 4 pages, 2 figure

Activity - Binary Code

A Binary Code activity and worksheet for CS0 students. Part of the CUNY CS04All project

Activity - A-Frame: Virtual Reality Programming

An A-Frame Virtual Reality Programming activity for CS0 students. Part of the CUNY CS04All project