Mangnon–phonon–photon interactions in cubic ferromagnets in the vicinity of orientational phase transition: Retrospective and phenomenological study

This work presents a comprehensive theoretical investigation of magnon–phonon–photon interactions in cubic ferromagnets near orientational phase transitions (OPTs). The study focuses on the interplay of magnetoelastic (ME), electromagnetic-spin (EMS), and acoustic–electromagnetic (AEM) interactions in ferromagnetic dielectrics and metals. By deriving dispersion equations for coupled waves, the research reveals how the dynamic properties of magnetically ordered crystals evolve in response to these interactions under varying external magnetic fields and near OPT points. The ME interaction prominently influences spin and elastic wave dynamics, giving rise to coupled modes, such as quasi-magnon and quasi-acoustic waves. Near the OPT, these interactions become dominant, leading to phenomena like the ME gap and the softening of vibrational modes. The EMS interaction significantly alters the activation energy and dispersion of quasi-spin and quasi-electromagnetic waves. In ferromagnetic metals, helicons (weakly damped electromagnetic waves) exhibit strong coupling with spin and elastic waves, particularly in the OPT region. The study identifies conditions for triple resonance among spin, elastic, and electromagnetic waves. Additionally, it explores the frequency-dependent rotation of polarization planes in electromagnetic and ME waves, which sharpens near the OPT points. These results provide a deeper understanding of the coupled dynamics in ferromagnetic materials, paving the way for new technological applications in spintronics, signal processing, and advanced magneto-optical devices. The theoretical framework developed here emphasizes the critical role of ME, EMS, and AEM interactions in tailoring wave properties for specific applications, particularly in designing next-generation magnetic and electronic systems.