3 research outputs found
Violation of the isotropic- approximation in overdoped La_{2-x}Sr_xCuO_4
Magnetotransport measurements on the overdoped cuprate La_{1.7}Sr_{0.3}CuO_4
are fitted using the Ong construction and band parameters inferred from
angle-resolved photoemission. Within a band picture, the low temperature Hall
data can only be fitted satisfactorily by invoking strong basal-plane
anisotropy in the mean-free-path . This violation of the isotropic-
approximation supports a picture of dominant small-angle elastic scattering in
cuprates due to out-of-plane substitutional disorder. We show that both band
anisotropy and anisotropy in the elastic scattering channel strongly
renormalize the Hall coefficient in overdoped La_{2-x}Sr_xCuO_4 over a wide
doping and temperature range.Comment: 4 pages, 4 figure
Evolution with hole doping of the electronic excitation spectrum in the cuprate superconductors
The recent scanning tunnelling results of Alldredge et al on Bi-2212 and of
Hanaguri et al on Na-CCOC are examined from the perspective of the BCS/BEC
boson-fermion resonant crossover model for the mixed-valent HTSC cuprates. The
model specifies the two energy scales controlling the development of HTSC
behaviour and the dichotomy often now alluded to between nodal and antinodal
phenomena in the HTSC cuprates. Indication is extracted from the data as to how
the choice of the particular HTSC system sees these two basic energy scales
(cursive-U, the local pair binding energy and, Delta-sc, the nodal BCS-like gap
parameter) evolve with doping and change in degree of metallization of the
structurally and electronically perturbed mixed-valent environment.Comment: 19 pages, 5 figure
Anomalous Transport Phenomena in Fermi Liquids with Strong Magnetic Fluctuations
In many strongly correlated electron systems, remarkable violation of the
relaxation time approximation (RTA) is observed. The most famous example would
be high-Tc superconductors (HTSCs), and similar anomalous transport phenomena
have been observed in metals near their antiferromagnetic (AF) quantum critical
point (QCP). Here, we develop a transport theory involving resistivity and Hall
coefficient on the basis of the microscopic Fermi liquid theory, by considering
the current vertex correction (CVC). In nearly AF Fermi liquids, the CVC
accounts for the significant enhancements in the Hall coefficient,
magnetoresistance, thermoelectric power, and Nernst coefficient in nearly AF
metals. According to the numerical study, aspects of anomalous transport
phenomena in HTSC are explained in a unified way by considering the CVC,
without introducing any fitting parameters; this strongly supports the idea
that HTSCs are Fermi liquids with strong AF fluctuations. In addition, the
striking \omega-dependence of the AC Hall coefficient and the remarkable
effects of impurities on the transport coefficients in HTSCs appear to fit
naturally into the present theory. The present theory also explains very
similar anomalous transport phenomena occurring in CeCoIn5 and CeRhIn5, which
is a heavy-fermion system near the AF QCP, and in the organic superconductor
\kappa-(BEDT-TTF).Comment: 100 pages, Rep. Prog. Phys. 71, 026501 (2008