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High field study of normal state magneto-transport in the thallium cuprate Tl-2201

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 Added by ul
 Publication date 1997
  fields Physics
and research's language is English




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We present a study of in-plane normal state magneto-transport in single crystal Tl-2201 in 60T pulsed magnetic fields. In optimally doped samples (Tc ~ 80K) the weak-magnetic-field regime extends to fields as high as 60T, but in overdoped samples (Tc ~ 30K) we are able to leave the weak field regime, as shown by the behavior of both the magnetoresistance and the Hall resistance. Data from samples of both dopings provide constraints on the class of model necessary to describe normal state transport in the cuprates.



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High temperature superconductors are strongly coupled systems which present a complicated phase diagram with many coexisting phases. This makes it difficult to understand the mechanism which generates their singular transport properties. Hydrodynamics, which mostly relies on the symmetries of the system without referring to any specific microscopic mechanism, constitutes a promising framework to analyze these materials. In this paper we show that in the strange metal phase of the cuprates, a whole set of transport coefficients are described by a universal hydrodynamic framework once one accounts for the effects of quantum critical charge density waves. We corroborate our theoretical prediction by measuring the DC transport properties of Bi-2201 close to optimal doping, proving the validity of our approach. Our argument can be used as a consistency check to understand the universality class governing the behavior of high temperature cuprate superconductors.
Upon doping, Mott insulators often exhibit symmetry breaking where charge carriers and their spins organize into patterns known as stripes. For high-Tc superconducting cuprates, stripes are widely suspected to exist in a fluctuating form. Here, we use numerically exact determinant quantum Monte Carlo calculations to demonstrate dynamical stripe correlations in the three-band Hubbard model, which represents the local electronic structure of the Cu-O plane. Our results, which are robust to varying parameters, cluster size, and boundary condition, strongly support the interpretation of a variety of experimental observations in terms of the physics of fluctuating stripes, including the hourglass magnetic dispersion and the Yamada plot of incommensurability vs. doping. These findings provide a novel perspective on the intertwined orders emerging from the cuprates normal state.
114 - G. Aeppli 1998
Polarized and unpolarized neutron scattering was used to measure the wave vector- and frequency-dependent magnetic fluctuations in the normal state (from the superconducting transition temperature, T_c=35, up to 350 K) of single crystals of La_{1.86}Sr_{0.14}CuO_4. The peaks which dominate the fluctuations have amplitudes that decrease as T^{-2} and widths that increase in proportion to the thermal energy, k_B T (where k_B is Boltzmanns constant), and energy transfer added in quadrature. The nearly singular fluctuations are consistent with a nearby quantum critical point.
Planar normal state resistivity data taken from three families of cuprate superconductors are compared with theoretical calculations from the recent extremely correlated Fermi liquid theory (ECFL). The two hole doped cuprate materials $LSCO$ and $BSLCO$ and the electron doped material $LCCO$ have yielded rich data sets at several densities $delta$ and temperatures T, thereby enabling a systematic comparison with theory. The recent ECFL resistivity calculations for the highly correlated $t$-$t$-$J$ model by us give the resistivity for a wide set of model parameters. After using X-ray diffraction and angle resolved photoemission data to fix parameters appearing in the theoretical resistivity, only one parameter, the magnitude of the hopping $t$, remains undetermined. For each data set, the slope of the experimental resistivity at a single temperature-density point is sufficient to determine $t$, and hence the resistivity on absolute scale at all remaining densities and temperatures. This procedure is shown to give a fair account of the entire data.
We report an angular quantum oscillation study of Tl_2Ba_2CuO_{6+delta} for two different doping levels (Tc = 10K and 26 K) and determine the Fermi surface size and topology in considerable detail. Our results show that Fermi liquid behavior is not confined to the edge of the superconducting dome and is robust up to at least T_c^{max}/3.5. Superconductivity is found to survive up to a larger doping p_c = 0.31 than in La_{2-x}Sr_xCuO_4. Our data imply that electronic inhomogeneity does not play a significant role in the loss of superconductivity and superfluid density in overdoped cuprates, and point towards a purely magnetic or electronic pairing mechanism
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