Electron transport in metal oxide superconducting heterojunctions

Abstract

Research results on electron transport in Au/YBa2Cu3Ox and Nb/Au/YBa2Cu3Ox thin-film heterojunctions are reviewed. The experimental current–phase relations of Nb/Au/YBa2Cu3Ox heterojunctions on c-oriented YBCO films exhibit a second harmonic, temperature dependence, and a phase shift that is explained in terms of a combined symmetry dx2−y2+s of the superconducting order parameter of YBa2Cu3Ox. The current–voltage characteristics of Au/YBa2Cu3Ox and Nb/Au/YBa2Cu3Ox heterojunctions on (1 1 20)YBa2Cu3Ox thin films with an inclined crystallographic c axis display an anomaly of the conductance at low voltages, the behavior of which is studied at various temperatures and magnetic fields. The experimental results are analyzed in the framework of a model for the appearance of bound states caused by multiple Andreev reflection in junctions containing a superconductor with dx2−y2 symmetry of the superconducting order parameter. Studies of the noise characteristics of Nb/Au/(1 1 20)YBa2Cu3Ox heterojunctions at T=4.2 K reveal the presence of thermal and shot components. However, enhancement of the shot noise due to multiple Andreev reflection is not observed in the experiment.

Superconducting current and low-energy states in a mesa-heterostructure interlayered with a strontium iridate film with strong spin-orbit interaction

“…experiment. An enhanced sensitivity of the superconducting current to magnetic field has been observed earlier for Josephson junctions with the antiferromagnetic Ca 0.5 Sr 0.5 CuO 2 interlayer [51] and was described by a specific orientation of a thick antiferromagnetic interlayer placed in between of the s-wave superconducting electrodes [52] which leads to the long-range spinsinglet Josephson effect. The d-wave component of the YBCO superconducting order parameter (∆ d ) promotes the unconventional superconducting CPR of the junctions (see Eq.…”

“…The ac Josephson effects in MS was revealed by measurements of I-V curves under electromagnetic radiation in mm frequency range. Since the characteristic frequency for MS The information on the CPR in MS could be obtained from the dynamics of Shapiro steps varying the power of microwave irradiation in conditions of high frequency limit f e >f C [51]. model [51,53] are also presented in Fig.…”

“…Since the characteristic frequency for MS The information on the CPR in MS could be obtained from the dynamics of Shapiro steps varying the power of microwave irradiation in conditions of high frequency limit f e >f C [51]. model [51,53] are also presented in Fig. 5c and Fig.…”