Hypergroups and Hypergroup Algebras

The survey contains a brief description of the ideas, constructions, results, and prospects of the theory of hypergroups and generalized translation operators. Representations of hypergroups are considered, being treated as continuous representations of topological hypergroup algebras.Comment: 52 page

Spin current and electrical polarization in GaN double-barrier structures

Tunnel spin polarization in a piezoelectric AlGaN/GaN double barrier structure is calculated. It is shown that the piezoelectric field and the spontaneous electrical polarization increase an efficiency of the tunnel spin injection. The relation between the electrical polarization and the spin orientation allows engineering a zero magnetic field spin injection manipulating the lattice-mismatch strain with an Al-content in the barriers.Comment: 13 pages, 6 figure