Zeroth-Order Nucleation Transition under Nanoscale Phase Separation

• Published in: Symmetry (Basel) Vol. 13; no. 12; p. 2379
• Main Authors: Yukalov, Vyacheslav I., Yukalova, Elizaveta P.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-12-2021
• Subjects: Ferromagnetic phases; Ferromagnetism; heterophase mixture; Hilbert space; Interaction parameters; Magnetic properties; nanoscale phase separation; Nucleation; nucleation point; Phase separation; Phase transitions; quasi-equilibrium system; zeroth-order transition
• ISSN: 2073-8994; 2073-8994
• DOI: 10.3390/sym13122379

Materials with nanoscale phase separation are considered. A system representing a heterophase mixture of ferromagnetic and paramagnetic phases is studied. After averaging over phase configurations, a renormalized Hamiltonian is derived describing the coexisting phases. The system is characterized by direct and exchange interactions and an external magnetic field. The properties of the system are studied numerically. The stability conditions define the stable state of the system. At a temperature of zero, the system is in a pure ferromagnetic state. However, at finite temperature, for some interaction parameters, the system can exhibit a zeroth-order nucleation transition between the pure ferromagnetic phase and the mixed state with coexisting ferromagnetic and paramagnetic phases. At the nucleation transition, the finite concentration of the paramagnetic phase appears via a jump.