Conductance studies on different types of Nb/Al, AlOx,(/A1)/Nb Josephson tunnel junctions

The conductance-voltage characteristics of different types of Josephson tunnel junctions have been measured at 4.2 K: symmetric Nb/Al, AlOx/Al/Nb, asymmetric Nb/Al, AlOx/Nb and Nb/Al/AlOx-/AlOx/Nb, containing a double oxidation layer. The symmetric junctions can be described very well by a trapezoidal potential barrier model. The asymmetric junctions show less agreement with theory. In these junctions resistance switching occurs, possibly due to charge trapping. The resistance is lower than in symmetric junctions. The conductance measurements on double oxidation layer junctions show, that this type of junction has an inhomogeneous oxide layer

Josephson junctions and DC SQUIDS based on Nb/Al technology

A process for fabricating high-quality Josephson junctions and DC SQUIDS on basis of Nb/Al technology has been developed. DC magnetron sputtering is used for the deposition of the metal layers and the barrier is formed by thermal oxidation of the Al-layer. The junction area of 5 µm × 5 5 µm is obtained using anodisation. Three types of Josephson tunnel junctions have been prepared: standard Nb/Al, AlOx/Nb, symmetric Nb/Al, AlOx, Al/Nb and Nb/Al, AlOx/AlOx/Nb, the latter having a double oxide layer. We performed current-voltage and conductance-voltage measurements at different temperatures and special attention was paid to the noise behaviour. Gap and sub-gap parameters as well as barrier parameters are presented. Three different DC SQUID configurations were developed on basis of the Nb/Al Josephson junctions. The measured characteristics of the standard Tesche-Clarke DC SQUID, the resistively shunted SQUID and the inductively shunted SQUID are compared with special attention being paid to the noise properties. A 19-channel DC SQUID magnetometer with standard and/or resistively-shunted DC SQUIDs is under construction

Magnetometers based on (double) relaxation oscillation SQUIDs

Relaxation Oscillation SQUIDs (ROS) and Double Relaxation Oscillation SQUIDS (DROS) combine the sensitivity of dc-SQUIDS with a large transfer, thus enabling flux locked loop operation with direct voltage readout by a room-temperature dc-amplifier, without flux modulation techniques. We fabricated several ROSs and DROSs with relaxation frequencies from 5 to 180 MHz. The experimental flux-to-frequency curves of the ROSs can well be fitted with theory, and the transfer (up to 170MHz/Φo) is large enough for practical use in a FLL without flux modulation. The experimental flux-to-voltage characteristics of the DROSs show very large transfer values of typically 10 to 30 mV/Φo. A DROS operated in a simple FLL with direct voltage readout showed a white noise level of about 2 µΦo/√Hz. A three channel DROS magnetometer system for biomagnetic measurements is under construction. In the DROSs that are to be used in this system, the signal flux is coupled to the SQUID by a tightly coupled 50-turn input coil

Laughter's influence on the intimacy of self-disclosure

If laughter functions to build relationships between individuals, as current theory suggests, laughter should be linked to interpersonal behaviors that have been shown to be critical to relationship development. Given the importance of disclosing behaviors in facilitating the development of intense social bonds, it is possible that the act of laughing may temporarily influence the laugher's willingness to disclose personal information. We tested this hypothesis experimentally by comparing the characteristics of self-disclosing statements produced by those who had previously watched one of three video clips that differed in the extent to which they elicited laughter and positive affect. The results show that disclosure intimacy is significantly higher after laughter than in the control condition, suggesting that this effect may be due, at least in part, to laughter itself and not simply to a change in positive affect. However, the disclosure intimacy effect was only found for observers' ratings of participants' disclosures and was absent in the participants' own ratings. We suggest that laughter increases people's willingness to disclose, but that they may not necessarily be aware that it is doing so