Reentrant resistance and giant Andreev backscattering in a two-dimensional electron gas coupled to superconductors

• Published in: Physica. B, Condensed matter Vol. 249; pp. 467 - 471
• Main Authors: den Hartog, S.G., van Wees, B.J., Nazarov, Yu.V., Klapwijk, T.M., Borghs, G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.1998
• Subjects: Quantum point contact; Superconducting proximity effect; Quantum point contact; Superconducting proximity effect
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/S0921-4526(98)00166-5

We first present the bias-voltage dependence of the superconducting phase-dependent reduction in the differential resistance of a disordered T-shaped two-dimensional electron gas (2DEG) coupled to two superconductors. This reduction exhibits a reentrant behavior, since it first increases upon lowering the bias voltage, exhibits a maximum for a bias voltage of about the Thouless energy and disappears almost completely at zero bias voltage. Second, we have investigated the superconducting-phase-modulated reduction in the resistance of a ballistic quantum point contact (QPC) connected via a disordered 2DEG to superconductors. We show that this reduction is caused by coherent Andreev backscattering of holes through the QPC, which increases monotonically by reducing the bias voltage to zero.