TY - JOUR
AB - Superconductivity in heavy-fermion systems has an unconventional nature and is considered to originate from the universal features of the electronic structure. Here, the Anderson lattice model is studied by means of the full variational Gutzwiller wave function incorporating nonlocal effects of the on-site interaction. We show that the d-wave superconducting ground state can be driven solely by interelectronic correlations. The proposed microscopic mechanism leads to a multigap superconductivity with the dominant contribution due to f electrons and in the dx2−y2-wave channel. Our results rationalize several important observations for CeCoIn5.
AU - Wysokiński, Marcin
AU - Kaczmarczyk, Jan
AU - Spałek, Jozef
ID - 1368
IS - 2
JF - Physical Review B - Condensed Matter and Materials Physics
TI - Correlation driven d wave superconductivity in Anderson lattice model: Two gaps
VL - 94
ER -
TY - JOUR
AB - Anisotropic dipole-dipole interactions between ultracold dipolar fermions break the symmetry of the Fermi surface and thereby deform it. Here we demonstrate that such a Fermi surface deformation induces a topological phase transition - the so-called Lifshitz transition - in the regime accessible to present-day experiments. We describe the impact of the Lifshitz transition on observable quantities such as the Fermi surface topology, the density-density correlation function, and the excitation spectrum of the system. The Lifshitz transition in ultracold atoms can be controlled by tuning the dipole orientation and, in contrast to the transition studied in crystalline solids, is completely interaction driven.
AU - Van Loon, Erik
AU - Katsnelson, Mikhail
AU - Chomaz, Lauriane
AU - Lemeshko, Mikhail
ID - 1416
IS - 19
JF - Physical Review B - Condensed Matter and Materials Physics
TI - Interaction-driven Lifshitz transition with dipolar fermions in optical lattices
VL - 93
ER -
TY - JOUR
AB - We study the superconducting phase of the Hubbard model using the Gutzwiller variational wave function (GWF) and the recently proposed diagrammatic expansion technique (DE-GWF). The DE-GWF method works on the level of the full GWF and in the thermodynamic limit. Here, we consider a finite-size system to study the accuracy of the results as a function of the system size (which is practically unrestricted). We show that the finite-size scaling used, e.g. in the variational Monte Carlo method can lead to significant, uncontrolled errors. The presented research is the first step towards applying the DE-GWF method in studies of inhomogeneous situations, including systems with impurities, defects, inhomogeneous phases, or disorder.
AU - Tomski, Andrzej
AU - Kaczmarczyk, Jan
ID - 1419
IS - 17
JF - Journal of Physics: Condensed Matter
TI - Gutzwiller wave function for finite systems: Superconductivity in the Hubbard model
VL - 28
ER -
TY - JOUR
AB - The two-photon 1s2 2s 2p 3P0 1s22s2 1S0 transition in berylliumlike ions is theoretically investigated within a fully relativistic framework and a second-order perturbation theory. We focus our analysis on how electron correlation, as well as the negative-energy spectrum, can affect the forbidden E1M1 decay rate. For this purpose, we include the electronic correlation via an effective local potential and within a single configuration-state model. Due to its experimental interest, evaluations of decay rates are performed for berylliumlike xenon and uranium. We find that the negative-energy contribution can be neglected at the present level of accuracy in the evaluation of the decay rate. On the other hand, if contributions of electronic correlation are not carefully taken into account, it may change the lifetime of the metastable state by up to 20%. By performing a full-relativistic jj-coupling calculation, we found a decrease of the decay rate by two orders of magnitude compared to non-relativistic LS-coupling calculations, for the selected heavy ions.
AU - Amaro, Pedro
AU - Fratini, Filippo
AU - Safari, Laleh
AU - Machado, Jorge
AU - Guerra, Mauro
AU - Indelicato, Paul
AU - Santos, José
ID - 1496
IS - 3
JF - Physical Review A - Atomic, Molecular, and Optical Physics
TI - Relativistic evaluation of the two-photon decay of the metastable 1s22s2p3P0 state in berylliumlike ions with an effective-potential model
VL - 93
ER -
TY - JOUR
AB - We investigate the quantum interference shifts between energetically close states, where the state structure is observed by laser spectroscopy. We report a compact and analytical expression that models the quantum interference induced shift for any admixture of circular polarization of the incident laser and angle of observation. An experimental scenario free of quantum interference can thus be predicted with this formula. Although this study is exemplified here for muonic deuterium, it can be applied to any other laser spectroscopy measurement of ns-n′p frequencies of a nonrelativistic atomic system, via an ns→n′p→n′′s scheme.
AU - Amaro, Pedro
AU - Fratini, Filippo
AU - Safari, Laleh
AU - Antognini, Aldo
AU - Indelicato, Paul
AU - Pohl, Randolf
AU - Santos, José
ID - 1587
IS - 6
JF - Physical Review A - Atomic, Molecular, and Optical Physics
TI - Quantum interference shifts in laser spectroscopy with elliptical polarization
VL - 92
ER -