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TT: Tiefe Temperaturen

TT 4: Josephson Kontakte

TT 4.9: Vortrag

Montag, 26. März 2001, 16:45–17:00, J

Gate-voltage and temperature dependence of the current-phase relation in Nb/2DES/Nb Josephson junctions on p-type InAs — •M. Ebel¹, R. Kürsten¹, T. Matsuyama¹, U. Merkt¹, E. Il’ichev², M. Grajcar², H.E. Hoenig², and H.-G. Meyer² — ¹Universität Hamburg, Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Jungiusstraße 11, D-20355 Hamburg, Germany — ²Institut für Physikalische Hochtechnologie, Winzerlaer Str. 10, D-07745 Jena, Germany

Current-phase relations (CPR) of Nb/2DES/Nb Josephson junctions on p-type InAs single crystals are investigated experimentally at various gate voltages in the temperature range 2 K≤ T≤ 4.2 K. The junctions are in equilibrium and the corresponding carrier density of the quasi-two-dimensional electron system is less than 1· 10¹² cm⁻² in the examined range of gate voltages. The junctions are incorporated into a washer-shaped superconducting loop with an inductance of about 80 pH that forms a single-junction interferometer. The loop is inductively coupled to a tank circuit with a resonance frequency of 17 MHz. The CPR is obtained from the measurement of the impedance of the phase-biased junction. The supercurrent in this type of the junctions is supposed to be carried by Andreev-bound states. For this coupling mechanism a non-sinusoidal form of the CPR is expected. Deviations from a sinusoidal CPR have been measured and are in accordance with theoretical predictions.