RESUMEN
Sub-Kelvin scanning tunneling spectroscopy in the Chevrel phases SnMo6S8 and PbMo6S8 reveals two distinct superconducting gaps with Δ1=3 meV, Δ2â¼1.0 meV and Δ1=3.1 meV, Δ2â¼1.4 meV, respectively. The gap distribution is strongly anisotropic, with Δ2 predominantly seen when scanning across unit-cell steps on the (001) sample surface. The spectra are well fitted by an anisotropic two-band BCS s-wave gap function. Our spectroscopic data are confirmed by electronic heat capacity measurements, which also provide evidence for a twin-gap scenario.
RESUMEN
A ferroelectric field effect in epitaxial thin film SrCuO(2)/Pb(Zr(0.52)Ti(0.48))O(3) heterostructures was observed. A 3.5 percent change in the resistance of a 40 angstrom SrCuO(2) layer (a parent high-temperature superconducting compound) was measured when the polarization field of the Pb(Zr(0.52)Ti(0.48))O(3) layer was reversed by the application of a pulse of small voltage (<5 volts). This effect, both reversible and nonvolatile, is attributed to the electric field-induced charge at the interface of SrCuO(2) and Pb(Zr(0.52)Ti(0.48))O(3). This completely epitaxial thin film approach shows the possibility of making nonvolatile, low-voltage ferroelectric field effect devices for both applications and fundamental studies of field-induced doping in novel compounds like SrCuO(2).