Phase transitions in random magnetic bilayer

The influence of random interlayer exchange on the phase states of the simplest magnetic heterostructure consisting of two ferromagnetic Ising layers with large interaction radius is studied. It is shown that such system can exist in three magnetic phases: ferromagnetic, antiferromagnetic and ferrimagnetic. The possible phase diagrams and temperature dependencies of thermodynamic parameters are described. The regions of existence of the magnetic phases in external magnetic field are determined at zero temperature.Comment: 6 pages, 4 figures; typos corrected, explanation of mechanism underlying the appearance of ferrimagnetic states adde

Phenomenological theory of nonergodic phenomena in dipole- and spin-glasses

The path-dependent magnetizations (polarizations) and susceptibilities in dipole- and spin-glasses are described analytically for the standard protocols of temperature and field variations using the phenomenological Landau-type description of multiple metastable states in the nonergodic phases. The immediate manifestation of metastable states' multiplicity as staircases of magnetizations (polarizations) curves in the temperature cycling experiments is explained and described. The obtained results are in a reasonable qualitative agreement with the existing experimental data.Comment: 12 pages, 9 figure