arXiv subjects

M. Abdel-Jawad

Publications and source records attributed to M. Abdel-Jawad.

5 recordsLinked to original sources

arXiv2015

Universality Class of the Mott Transition

Pressure dependence of the conductivity and thermoelectric power is measured through the Mott transition in the layer organic conductor EtMe3P[Pd(dmit)2]2. The critical behavior of the thermoelectric effect provides a clear and objective determination of the Mott-Hubbard transition during the isothermal pressure sweep. Above the critical end point, the metal-insulator crossing, determined by the thermoelectric effect minimum value, is not found to coincide with the maximum of the derivative of the conductivity as a function of pressure. We show that the critical exponents of the Mott-Hubbard transition fall within the Ising universality class regardless of the dimensionality of the system.

cond-mat.str-el↗

arXiv2007

Correlation between $T_c$ and anisotropic scattering in Tl$_2$Ba$_2$CuO$_{6+δ}$

Angle-dependent magnetoresistance measurements are used to determine the isotropic and anisotropic components of the transport scattering rate in overdoped Tl$_2$Ba$_2$CuO$_{6+δ}$ for a range of $T_c$ values between 15K and 35K. The size of the anisotropic scattering term is found to scale linearly with $T_c$, establishing a link between the superconducting and normal state physics. Comparison with results from angle resolved photoemission spectroscopy indicates that the transport and quasiparticle lifetimes are distinct.

cond-mat.supr-con↗

arXiv2007

Angle dependent magnetoresistance measurements in Tl$_2$Ba$_2$CuO$_{6+δ}$ and the need for anisotropic scattering

The angle-dependent interlayer magnetoresistance of overdoped Tl$_2$Ba$_2$CuO$_{6+δ}$ has been measured in high magnetic fields up to 45 Tesla. A conventional Boltzmann transport analysis with no basal-plane anisotropy in the cyclotron frequency $ω_c$ or transport lifetime $τ$ is shown to be inadequate for explaining the data. We describe in detail how the analysis can be modified to incorporate in-plane anisotropy in these two key quantities and extract the degree of anisotropy for each by assuming a simple four-fold symmetry. While anisotropy in $ω_c$ and other Fermi surface parameters may improve the fit, we demonstrate that the most important anisotropy is that in the transport lifetime, thus confirming its role in the physics of overdoped superconducting cuprates.

cond-mat.supr-con↗

arXiv2006

Anisotropic Scattering and Anomalous Transport in a High Temperature Superconductor

The metallic state of high temperature cuprate superconductors is markedly different from that of textbook metals. The origin of this unconventional state, characterized by unusual and distinct temperature dependences in the transport properties, remains unresolved despite intense theoretical efforts. Our understanding is impaired by our inability to determine experimentally the temperature and momentum dependence of the transport scattering rate. Here we use a novel magnetotransport probe to show that the unusual temperature dependences of the resistivity and the Hall coefficient in highly doped Tl$_2$Ba$_2$CuO$_{6+δ}$ originate from two distinct inelastic scattering channels. One channel is due to conventional electron-electron scattering whilst the other is highly anisotropic, has the same symmetry as the superconducting gap and a magnitude that grows approximately linearly with temperature. The observed form and anisotropy put tight constraints on theories of the metallic state. Moreover, in heavily doped non-superconducting cuprates, this anisotropic scattering term appears to be absent, suggesting an intimate connection between the origin of this scattering and superconductivity itself.

cond-mat.supr-con↗

arXiv2004

Magnetic-field-induced Fermi surface reconstruction in Na$_{0.5}$CoO$_2$

We have performed electrical transport measurements at low temperatures and high magnetic fields in Na$_{0.5}$CoO$_2$ single crystals. Shubnikov de Haas oscillations were observed for two frequencies F_1 150 and F_2 40 T corresponding respectively to 1 and .25% of the area of the orthorhombic Brillouin zone. These small Fermi surface (FS) pockets indicate that most of the original FS vanishes at the charge ordering (CO) transition. Furthermore, in-plane magnetic fields strongly suppress the CO state. For fields rotating within the conducting planes we observe angular magnetoresistance oscillations (AMRO), whose periodicity changes from two- to six-fold at the transition, suggesting that a reconstructed hexagonal FS emerges at a field of about 40 T.

cond-mat.str-el↗