Amorphous-amorphous transition and the two-step replica symmetry breaking phase

The nature of polyamorphism and amorphous-to-amorphous transitions is investigated by means of an exactly solvable model with quenched disorder, the spherical s + p multispin interaction model. The analysis is carried out in the framework of replica symmetry breaking theory and leads to the identification of low-temperature glass phases of different kinds. Besides the usual one-step solution, known to reproduce all basic properties of structural glasses, also a physically consistent two-step solution arises. More complicated phases are found as well, as temperature is further decreased, expressing a complex variety of metastable-state structures for amorphous systems.