77 research outputs found
Magnetic instability of a two-dimensional Anderson non-Fermi liquid
We show that in the Anderson model for a two-dimensional non-Fermi liquid a
magnetic instability can lead to the itinerant electron ferromagnetism. The
critical temperature and the susceptibility of the paramagnetic phase have been
analytically calculated. The usual Fermi behaviour is re-obtained taking the
anomalous exponent to be zero.Comment: 3 pages, Revte
Specific heat behavior of high temperature superconductors in the pseudogap regime
Experimental data obtained from thermodynamic measurements in underdoped high
temperature superconductors show unusual anomalies in the temperature
dependence of the electronic specific heat both in the normal state and at the
critical point associated to the superconducting phase transition. The observed
deviations from the standard behavior are probably linked with the opening of a
pseudogap in the energy spectrum of the single-particle excitations associated
with the normal state. Based on a phenomenological description of the pseudogap
phase we perform analytical and numerical calculations for the temperature
dependence of the specific heat for both the superconducting and normal state.
The reduced specific heat jump at the transition point can be explained by a
modified electronic single particle contribution to the specific heat in the
presence of the normal state pseudogap. The hump observed in the normal state
specific heat can be explained by the electronic pair contribution associated
with strong fluctuations of the order parameter in the critical region. The
obtained theoretical results are discussed in connection with experimental data
for cuprates.Comment: 7 pages, 3 EPS figures. to appear in EPJ
Fluctuation conductivity in layered d-wave superconductors near critical disorder
We consider the fluctuation conductivity in the critical region of a disorder
induced quantum phase transition in layered d-wave superconductors. We
specifically address the fluctuation contribution to the system's conductivity
in the limit of large (quasi-two-dimensional system) and small
(quasi-three-dimensional system) separation between adjacent layers of the
system. Both in-plane and c-axis conductivities were discussed near the point
of insulator-superconductor phase transition. The value of the dynamical
critical exponent, , permits a perturbative treatment of this quantum
phase transition under the renormalization group approach. We discuss our
results for the system conductivities in the critical region as function of
temperature and disorder.Comment: Final version to be published in Eur. Phys. J.
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