Tunneling conductance spectra of normal metal/insulator/superconductor (N/I/S) junctions are calculated to determine the potential of tunneling spectroscopy in investigations of topological superconductivity. Peculiar feature of topological supercond
uctors is the formation of gapless edge states in them. Since the conductance of N/I/S junctions is sensitive to the formation of these edge states, topological superconductivity can be identified through edge-state detection. Herein, the effects of Fermi surface anisotropy and an applied magnetic field on the conductance spectra are analyzed to gather indications that can help to identify the topological nature of actual materials.
To search for new evidence of the chiral p-wave superconducting domain in Sr2RuO4, we investigated the unconventional local transport characteristics of a microfabricated Sr2RuO4-Ru eutectic junction. We found that the anomalous hysteresis in voltage
-current characteristics [as reported in H. Kambara et al.: Phys. Rev. Lett. 101 (2008) 267003.] is strongly affected by dc currents, but not by magnetic fields. This suggests that dc current acts as a driving force to move chiral p-wave domain walls; a domain wall trapped at a pinning potential is forced to shift to the next stable position, thereby forming a larger critical current path and resulting in the anomalous hysteresis.
We study the dynamics of multi-junction switching (MJS): several intrinsic Josephson junctions (IJJs) in an array switch to the finite voltage state simultaneously. The number of multi-switching junctions ($N$) was successfully tuned by changing the
load resistance serially connected to an Bi$_2$Sr$_{1.6}$La$_{0.4}$CuO$_{6+delta}$ IJJ array. The independence of the escape rates of $N$ in the macroscopic quantum tunneling regime indicates that MJS is a $successive$ switching process rather than a $collective$ process. The origin of MJS is explained by the gradient of a load curve and the relative magnitudes of the switching currents of quasiparticle branches in the current-voltage plane.
