Magnetic states of an isotropic magnet with the “large” ion spin S = 3/2

• Published in: Physics of the solid state Vol. 58; no. 7; pp. 1384 - 1392
• Main Authors: Orlenko, E. V., Orlenko, F. E.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-07-2016; Springer
• Subjects: Ferromagnetism; Magnetism; Physics; Physics and Astronomy; Solid State Physics
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S1063783416070271

The magnetic state of a system of particles with a “large” spin of 3/2 in the presence of isotropic exchange interaction in the system has been studied on the basis of a derived spin Hamiltonian. It has been shown that, at a positive contribution of the exchange interaction, an unstable nematic state appears and transforms to a stable ferromagnetic state (with an average spin of 3/2). The excitation spectrum in the ferromagnetic state is a triply degenerate Goldstone-type gapless magnon mode. At a negative sign of the exchange contribution, an antinematic state is stable with respect to a transition to a ferromagnetic state, which is forbidden. In this case, the antinematic always occurs in the state of a phase transition to an unstable antiferromagnetic state, the excitation spectrum of which is characterized by a single nondegenerate Goldstone mode.