arXiv subjects

J. G. Storey

Publications and source records attributed to J. G. Storey.

22 records · Page 2Linked to original sources

arXiv2007

Pressure dependence of the oxygen isotope effect in YBa$_2$Cu$_4$O$_8$

We have carried out measurements of the pressure dependence to 1.2 GPa of the oxygen isotope effect on $T_c$ in the high-$T_c$ superconductor YBa$_2$Cu$_4$O$_8$ using a clamp cell in a SQUID magnetometer. This compound lies close to, but just above, the 1/8$^{th}$ doping point where in La$_{2-x}$Sr$_x$CuO$_4$ marked anomalies in isotope effects occur. Both isotopes show the same very large pressure dependence of $T_c$ with the result that the isotope exponent remains low ($\sim$0.08) but increases slightly with increasing pressure. This is discussed in terms of stripe suppression, a competing pseudogap and the effect of superconducting fluctuations.

cond-mat.supr-con↗

arXiv2007

Saddle-point van Hove singularity and the phase diagram of high-Tc cuprates

We examine the generic phase behavior of high-Tc cuprate superconductors in terms a universal van Hove singularity in the strongly overdoped region. Using a rigid ARPES-derived dispersion we solve the BCS gap equation and show that the pairing interaction or pairing energy cutoff must be a rapidly declining function of doping. This result is prejudicial to a phonon-based pairing interaction and more consistent with a magnetic or magnetically enhanced interaction.

cond-mat.supr-con↗

arXiv2007

Fermi arcs in cuprate superconductors: tracking the pseudogap below Tc and above T*

Using an energy-momentum dispersion for Bi2Sr2CaCu2O8 obtained from angle-resolved photoelectron spectroscopy we show that the shrinking Fermi arc model of the pseudogap is inconsistent with Raman scattering below Tc and specific heat near T*. By simulating the quasiparticle energy dispersion curves we show that Fermi arcs are an artifact of a T-dependent scattering rate.

cond-mat.supr-con↗

arXiv2007

Thermodynamic properties of Bi2Sr2CaCu2O8 calculated from the electronic dispersion

The electronic dispersion for Bi2Sr2CaCu2O(8+d) has been determined from angle-resolved photoelectron spectroscopy (ARPES). From this dispersion we calculate the entropy and superfluid density. Even with no adjustable parameters we obtain an exceptional match with experimental data across the entire phase diagram, thus indirectly confirming both the ARPES and thermodynamic data. The van Hove singularity is crossed in the overdoped region giving a distinctive linear-in-T temperature dependence in the superfluid density there.

cond-mat.supr-con↗