Table of contents

Here, we review the history, theory, measurement technique and experimental results on gyrotropic phenomena including optical rotation (optical activity), electrogyration, the Faraday effect and magneto-electrogyration in transparent crystals, including examples of structural phase transitions. Relations to the absolute structure are discussed and model calculations are performed on the basis of electronic polarizability and crystal structure.

Recent studies on high-T_c superconductors have aroused new interest in tunnelling effects in unconventional superconductors. Unlike in conventional s-wave superconductors, the d-wave pairing state in these materials has an internal phase of the pair potential. The internal phase as a function of the wavevector of the Cooper pairs has a large influence on the electric properties of tunnelling junctions. Important effects of the internal phase on the Josephson current were first predicted theoretically. The idea has been established through several experiments using high-T_c Josephson junctions, which detect π-phase shift between the a- and b-axis directions and fractional flux quanta. These results give convincing evidence for d-wave symmetry in high-T_c superconductors. In addition, the existence of new interference effects in the quasiparticle states near surfaces and boundaries has been suggested through theoretical predictions. Experimentally, a large number of tunnelling spectroscopy data showed zero-bias conductance peaks (ZBCPs), the origin of which cannot be explained in terms of the classical concept that a tunnelling conductance spectrum is a phase-insensitive probe of the electronic states. It is clarified theoretically that the observed ZBCPs reflect the formation of zero-energy states on the surface due to the π-phase shift of internal phase in the d-wave pairing symmetry. The formulation developed for tunnelling spectroscopy suggests that tunnelling spectroscopy is essentially phase sensitive. In addition, the formation of the bound states has been shown to have a serious influence on the electrical properties of Josephson junctions. Several anomalous properties including strong enhancement of the Josephson current in the low-temperature region have been predicted theoretically. In this report, recent developments in tunnelling effects on surface bound states in unconventional superconductors are reviewed.

X-ray scattering investigations of surfaces and interfaces in soft-condensed matter are reviewed. Both high-resolution structural determinations in the direct space and investigations of fluctuations with long-range correlations requiring a high resolution in the Fourier space are discussed. All the scattering cross-sections for diffraction or diffuse scattering are derived within a unified frame, and the experimental aspects related to their measurement are discussed in detail. The general principles are illustrated by various examples of studies of the liquid-vapour interface, Langmuir and Langmuir-Blodgett films, wetting films, polymer films, liquid crystals and liquid-liquid interfaces.