Condensed Matter Physics, 2010, том 13

XI-th Workshop and Awards for young researchers in the field of statistical physics and condensed matter theory

2012-04-10T09:12:37Z

XI-th Workshop and Awards for young researchers in the field of statistical physics and condensed matter theory The XI-th Anniversary Workshop will be held in Lviv at the Institute for Condensed Matter Physics on June 1–3, 2011.

Author index of volume13 (2010)

2012-04-10T09:13:40Z

Author index of volume13 (2010)

Superconducting states in strongly correlated systems with nonstandard quasiparticles and real space pairing: an unconventional Fermi-liquid limit

2012-04-10T09:19:41Z

Superconducting states in strongly correlated systems with nonstandard quasiparticles and real space pairing: an unconventional Fermi-liquid limit Spałek, J. We use the concept of generalized (almost localized) Fermi Liquid composed of nonstandard quasiparticles with spin-dependence effective masses and the effective field induced by electron correlations. This Fermi liquid is obtained within the so-called statistically-consistent Gutzwiller approximation (SGA) proposed recently [cf. J. Je¸drak et al., arXiv: 1008.0021] and describes electronic states of the correlated quantum liquid. Particular emphasis is put on real space pairing driven by the electronic correlations, the Fulde-Ferrell state of the heavy-fermion liquid, and the d-wave superconducting state of high temperature cuprate superconductors in the overdoped limit. The appropriate phase diagrams are discussed showing in particular the limits of stability of the Bardeen-Cooper-Schrieffer (BCS) type of state.; Використано концепцію узагальненої (майже локалізованої) Фермі рідини, що складається з нестандартних квазічастинок із спін залежними ефективними масами та ефективним полем, індукованим електронними кореляціями. Фермі рідину одержано в межах так званого статистично-узгодженого наближення Гутцвіллера, що недавно запропоноване [cf. J. Jedrak et al., arXiv: 1008.0021] і описує електронні стани скорельованої квантової рідини. Розглянуто спарювання у реальному просторі, яке викликане електронними кореляціями, стані Фульде - Феррелла важкої ферміонної рідини і d-хвильовому надпровідному стані високотемпературних мідних надпровідників у випадку перелегування. Розглянуто відповідну фазову діаграму, яка демонструє, зокрема, межі стійкості станів типу Бардіна - Купера - Шріффера.

Analysis of the 3d massive renormalization group perturbative expansions: a delicate case

2012-04-10T09:19:07Z

Analysis of the 3d massive renormalization group perturbative expansions: a delicate case Delamotte, B.; Dudka, M.; Holovatch, Yu.; Mouhanna, D. The effectiveness of the perturbative renormalization group approach at fixed space dimension d in the theory of critical phenomena is analyzed. Three models are considered: the O(N) model, the cubic model and the antiferromagnetic model defined on the stacked triangular lattice. We consider all models at fixed d = 3 and analyze the resummation procedures currently used to compute the critical exponents. We first show that, for the O(N) model, the resummation does not eliminate all non-physical (spurious) fixed points (FPs). Then the dependence of spurious as well as of the Wilson-Fisher FPs on the resummation parameters is carefully studied. The critical exponents at the Wilson-Fisher FP show a weak dependence on the resummation parameters. On the contrary, the exponents at the spurious FP as well as its very existence are strongly dependent on these parameters. For the cubic model, a new stable FP is found and its properties depend also strongly on the resummation parameters. It appears to be spurious, as expected. As for the frustrated models, there are two cases depending on the value of the number of spin components. When N is greater than a critical value Nc, the stable FP shows common characteristic with the Wilson-Fisher FP. On the contrary, for N < Nc, the results obtained at the stable FP are similar to those obtained at the spurious FPs of the O(N) and cubic models. We conclude from this analysis that the stable FP found for N < Nc in frustrated models is spurious. Since Nc > 3, we conclude that the transitions for XY and Heisenberg frustrated magnets are of first order.