Random anisotropy disorder in superfluid 3He-A in aerogel

The anisotropic superfluid 3He-A in aerogel provides an interesting example of a system with continuous symmetry in the presence of random anisotropy disorder. Recent NMR experiments allow us to discuss two regimes of the orientational disorder, which have different NMR properties. One of them, the (s)-state, is identified as the pure Larkin-Imry-Ma state. The structure of another state, the (f)-state, is not very clear: probably it is the Larkin-Imry-Ma state contaminated by the network of the topological defects pinned by aerogel.Comment: JETP Lett. style, 6 pages, no figures, discussion extended, references added, version to be published in JETP Letter

Celebration of the Periodic Table of the Elements at the Academy of Sciences of Lisbon. A Chemistry Symposium Sublime Generalization: Discovery of The Periodic Law

info:eu-repo/semantics/publishedVersio

Molecular dynamics modelling of boundary migration in bicrystals under nanoburnishing

The paper reports the molecular dynamics simulation results on the behavior of a copper crystallite in local frictional contact. The crystallite has a perfect defect-free structure and contains a high-angle grain boundary of type Σ5. The influence of the initial structure on the specimen behavior under loading was analyzed. It is shown that nanoblocks are formed in the subsurface layer. The atomic mechanism of nanofragmentation was studied. A detailed analysis of atomic displacements in the blocks showed that the displacements are rotational. Calculations revealed that the miso ientation angle of formed nanoblocks along different directions does not exceed 2 degrees

Nonmonotonic magnetoresistance of a two-dimensional viscous electron-hole fluid in a confined geometry

Ultra-pure conductors may exhibit hydrodynamic transport where the collective motion of charge carriers resembles the flow of a viscous fluid. In a confined geometry (e.g., in ultra-high quality nanostructures) the electronic fluid assumes a Poiseuille-like flow. Applying an external magnetic field tends to diminish viscous effects leading to large negative magnetoresistance. In two-component systems near charge neutrality the hydrodynamic flow of charge carriers is strongly affected by the mutual friction between the two constituents. At low fields, the magnetoresistance is negative, however at high fields the interplay between electron-hole scattering, recombination, and viscosity results in a dramatic change of the flow profile: the magnetoresistance changes its sign and eventually becomes linear in very high fields. This novel non-monotonic magnetoresistance can be used as a fingerprint to detect viscous flow in two-component conducting systems.Comment: 10 pages, 8 figure