Publications

1995

1. Direct measurement of shear forces between polymerbearing surfaces sliding past each other

   Klein J., Kumacheva E., Mahalu D. & Perahia D. (1995) Macromolecular Symposia. 98, 1, p. 1149-1158  Abstract

   We have used a recently developed surface force balance to measure, with extreme sensitivity, both lateral and normal forces between interacting surfaces, for the case of simple liquids and particularly with surfaceattached polymers. The presence of polymers on the surfaces reduces drastically the force required to maintain them in sliding motion, under a given normal load, relative to the bare surface case. We believe this is due to the long range steric repulsion which can sustain a large normal load while maintaining a very fluid interfacial layer. The effect is much more marked for endtethered chains in a good solvent than for adsorbed chains in a θsolvent. This is attributed to the different extents of interpenetration of the compressed polymer layers.

2. Coherence and phase sensitive measurements in a quantum dot

   Yacoby A., Heiblum M., Mahalu D. & Shtrikman H. (1995) Physical review letters. 74, 20, p. 4047-4050  Abstract

   Via a novel interference experiment, which measures magnitude and phase of the transmission coefficient through a quantum dot in the Coulomb regime, we prove directly, for the first time, that transport through the dot has a coherent component. We find the same phase of the transmission coefficient at successive Coulomb peaks, each representing a different number of electrons in the dot; however, as we scan through a single Coulomb peak we find an abrupt phase change of . The observed behavior of the phase cannot be understood in the single particle framework.

3. Temporal correlation of electrons: Suppression of shot noise in a ballistic quantum point contact

   Reznikov M., Heiblum M., Shtrikman H. & Mahalu D. (1995) Physical review letters. 75, 18, p. 3340-3343  Abstract

   Wideband shot noise, associated with dc current flow through a quantum point contact (QPC), is measured in the microwave frequency range of 8-18 GHz. As the number of conducting channels in the QPC changes the noise power oscillates. Consistent with existing theories, the noise peaks depend linearly on the dc current. Surprisingly, however, in the pinch off region, where QPC is expected to behave as a classical injector, we find strong noise suppression, possibly mediated by the Coulomb interaction.