The intermediate state of a type-I superconductor involves a fine-scale mixture of normal and superconducting domains. We take the viewpoint, due to Landau, that the realizable domain patterns are (local) minima of a nonconvex variational problem. We examine the scaling law of the minimum energy and the qualitative properties of domain patterns achieving that law. Our analysis is restricted to ...

Using an atomic force microscope to nanopattern a substrate for liquid crystal alignment, a bend distortion is imposed on a liquid crystal. In regions of large bend the smectic-A phase melts into the nematic phase, and the width of the melted region is measured as a function of temperature. The results are consistent with type-I superconducting (nematic — smectic-A) behavior, wherein a large ma...

We investigate the crossed Andreev reflections between two graphene leads connected by a narrow superconductor. When the leads are, respectively, of the n and p type, we find that electron elastic cotunneling and local Andreev reflection are both eliminated even in the absence of any valley-isospin or spin polarizations. We further predict oscillations of both diagonal and cross conductances as...

In this research, we aim to clarify the relationship between the structural distortion due to doping and the superconductivity existence in the FeAs4 structure. For this, we have prepared polycrystalline of NdFeAsO0.8F0.2, NdFeAs0.95Sb0.05O0.8F0.2 and Nd0.99Ca0.01FeAsO0.8F0.2 samples by one-step solid state reaction method. The structural and electrical properties of the samples were characteri...

We develop a theory of current–voltage (I-U) characteristics for superconductor-normal metal-superconductor (SNS) junctions. At small voltages and sufficiently low temperatures the I-U junction is controlled by inelastic relaxation time τin. In particular, linear conductance proportional to this regime can be expressed solely in terms dependence density states normal region ν(χ) on phase differ...