Abstract:
The current configurations and the profile of the magnetic field penetrating into a 3D ordered Josephson medium are calculated for $I<I_C$. The calculation algorithm (modified for finite-length samples) is based on analyzing the continuous variation of the configuration toward a decrease in the Gibbs potential. This algorithm makes it possible to find a configuration into which the Meissner state passes when $I<I_C$ and an external field slightly exceeds $H_{\mathrm{max}}$ and trace the evolution of this configuration with a further rise in the field. At $H>H_{\mathrm{max}}$, the magnetic field penetrates into the sample as a quasi-uniform sequence of plane vortices. When $H$ is roughly equal to $H_0/2$, where $H_0$ is the outer field at which one fluxoid $\Phi_0$ passes through each cell, the plane vortices disintegrate into linear ones centered in cells neighboring along the diagonal. As the field grows, the vortex pattern condenses: zero-fluxoid cells are gradually “filled” starting from the boundary. When the field approaches $H_0$, a sequence of plane vortices centered in adjacent rows arises near the boundary. With a further increase in the field, sequences of linear vortices with a double fluxoid form at the boundary. Then, such a scenario is periodically repeated with a period $H_0$ in the external field.
Fulltext:
PDF file (221 kB)
