2,313 research outputs found
Tunneling into the normal state of Pr(2-x)CexCuO4
The temperature dependence of the tunneling conductance was measured for
various doping levels of Pr(2-x)CexCuO4 using planar junctions. A normal state
gap is seen at all doping levels studied, x=0.11 to x=0.19. We find it to
vanish above a certain temperature T*. T* is greater than Tc for the underdoped
region and it follows Tc on the overdoped side. This behavior suggests finite
pairing amplitude above Tc on the underdoped side
Tuning spin-orbit coupling and superconductivity at the SrTiO3/LaAlO3 interface: a magneto-transport study
The superconducting transition temperature, Tc, of the SrTiO3/LaAlO3
interface was varied by the electric field effect. The anisotropy of the upper
critical field and the normal state magneto-transport were studied as a
function of gate voltage. The spin-orbit coupling energy is extracted. This
tunable energy scale is used to explain the strong gate dependence of the
mobility and of the anomalous Hall signal observed. The spin-orbit coupling
energy follows Tc for the electric field range under study
Shubnikov-de Haas oscillations in SrTiO3\LaAlO3 interface
Quantum magnetic oscillations in SrTiO3/\LaAlO3 interface are observed. The
evolution of their frequency and amplitude at various gate voltages and
temperatures is studied. The data are consistent with the Shubnikov de-Haas
theory. The Hall resistivity rho exhibits nonlinearity at low magnetic field.
It is fitted assuming multiple carrier contributions. The comparison between
the mobile carrier density inferred from the Hall data and the oscillation
frequency suggests multiple valley and spin degeneracy. The small amplitude of
the oscillations is discussed in the framework of the multiple band scenario
Phase coherent transport in SrTiO3/LaAlO3 interfaces
The two dimensional electron gas formed between the two band insulators
SrTiO3 and LaAlO3 exhibits a variety of interesting physical properties which
make it an appealing material for use in future spintronics and/or quantum
computing devices. For this kind of applications electrons have to retain their
phase memory for sufficiently long times or length. Using a mesoscopic size
device we were able to extract the phase coherence length, and its temperature
variation. We find the dephasing rate to have a power law dependence on
temperature. The power depends on the temperature range studied and sheet
resistance as expected from dephasing due to strong electron-electron
interactions.Comment: Submitted to Phys. Rev
Role of oxygen in the electron-doped superconducting cuprates
We report on resistivity and Hall measurements in thin films of the
electron-doped superconducting cuprate PrCeCuO.
Comparisons between x = 0.17 samples subjected to either ion-irradiation or
oxygenation demonstrate that changing the oxygen content has two separable
effects: 1) a doping effect similar to that of cerium, and 2) a disorder
effect. These results are consistent with prior speculations that apical oxygen
removal is necessary to achieve superconductivity in this compound.Comment: 5 pages, 5 figure
Infrared Signature of the Superconducting State in Pr(2-x)Ce(x)CuO(4)
We measured the far infrared reflectivity of two superconducting
Pr(2-x)Ce(x)CuO(4) films above and below Tc. The reflectivity in the
superconducting state increases and the optical conductivity drops at low
energies, in agreement with the opening of a (possibly) anisotropic
superconducting gap. The maximum energy of the gap scales roughly with Tc as 2
Delta_{max} / kB Tc ~ 4.7. We determined absolute values of the penetration
depth at 5 K as lambda_{ab} = (3300 +/- 700) A for x = 0.15 and lambda_{ab} =
(2000 +/- 300) A for x = 0.17. A spectral weight analysis shows that the
Ferrell-Glover-Tinkham sum rule is satisfied at conventional low energy scales
\~ 4 Delta_{max}.Comment: 4 pages, 4 figure
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