Laminar Domain Structure Research Articles

Second-harmonic generation in a Fibonacci optical superlattice and the dispersive effect of the refractive index.

A Fibonacci optical superlattice is analyzed which is made from a single crystal with quasiperiodic laminar ferroelectric domain structures. The second-harmonic generation in this system is studied. Because of the dispersive effect of the refractive index, the second-harmonic spectrum does not reflect the symmetry of the quasiperiodic structure and thus does not exhibit self-similarity. The existence of the extinction phenomenon constitutes one major difference between our system and heterostructure systems. A general extinction rule is also obtained.

On the domain structure near the penetration field of the intermediate state in type‐I superconductors

AbstractThe radius r and the distance a of the flux tubes in the triangular flux‐tube lattice of type‐I superconductors are determined within the framework of the Ginzburg‐Landau theory as functions of the applied magnetic field, the surface energy parameter, Δ, and the thickness, L, of a superconducting layer in the limit N → 1 (N demagnetizing coefficient of the sample, 0 ≤ N≤ 1). It is shown that near the penetration field of the intermediate state the Gibbs free energy of the flux‐tube structure is lower than that of a laminar domain structure.

The interphase surface energy of superconducting niobium

The intermediate-mixed state laminar domain structure has been decorated on high purity dished niobium discs at 4.2°K. The Landau-Lifshitz-Sharvin theory is tested and used and the interphase surface energy is estimated at (3.7 ± 0.9) × 10 -3 ergs cm -2.