We report measurements of the temperature dependence of both in-plane and out-of-plane penetration depths (lambda(a) and lambda(c), respectively) in 2H-NbSe2. Measurements were made with a radio-frequency tunnel diode oscillator circuit at temperatures down to 100 mK. Analysis of the anisotropic superfluid density shows that a reduced energy gap is located on one or more of the quasi-two-dimensional Nb Fermi surface sheets rather than on the Se sheet, in contrast with some previous reports. This result suggests that the gap structure is not simply related to the weak electron-phonon coupling on the Se sheet and is therefore important for microscopic models of anisotropic superconductivity in this compound.

In-and out-of-plane London penetration depths were measured in single crystals CaAlSi ( Tc = 6.2 K and 7.3 K) using a tunnel-diode resonator. A full 3D BCS analysis of the superfluid density is consistent with a prolate spheroidal gap, with a weak-coupling BCS value in the ab-plane and stronger coupling along the c−axis. The gap anisotropy was found to significantly decrease for higher Tc samples.

Giannetta, R. W.; Olheiser, T. A.; Hannan, M.; Adesida, I.; and Melloch, Michael R., "Conductance quantization and zero bias peak in a gated quantum wire" (2005 AbstractConductance measurements are reported for an 0.4 mm wide GaAs/AlGaAs quantum wire with 7 cross-channel gates. The device exhibited integral conductance steps, magnetoconductance plateaus in agreement with the multiprobe formula and a conductance feature at 0.65(2e 2 /h). Differential conductance measurements down to 50 mK revealed a zero bias conductance peak that vanished with an in-plane field of 1 T. The width of this peak was comparable to that reported in high mobility quantum point contacts (Phys. Rev. Lett. 88 (2002) 226805). At low conductances this device also exhibited single electron charging characteristic of a multiple quantum dot. r

Measurements of the interlayer penetration depth Ќ have been performed on single crystals of the organic superconductors -͑ET͒ 2 Cu͓N͑CN͒ 2 ͔Br and -͑ET͒ 2 Cu͑NCS͒ 2 . We find that Ќ ͑0͒Ϸ130 m for both materials. The normalized superfluid density Ќ = ͓ Ќ ͑0͒ / Ќ ͑T͔͒ 2 may be fit equally well to a power law 1 − Ќ ϳ T n with n = 1.3-1.5 or to the form 1 − Ќ = ␣͑T 2 / T C ͒ / ͑T + T ‫ء‬ ͒, consistent with a d-wave pairing state with impurity scattering. The data imply coherent transport between conducting planes, in agreement with recent magnetoresistive measurements ͓J.

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