Fizika Nizkikh Temperatur: Volume 45, Number 9 (September 2019), p. 1095-1129 ( to contents , go back )
Ultrafast spin dynamics and spintronics for ferrimagnets close to the spin compensation point (Review Article)
Institute of Magnetism, NASU, 36-B Vernadskii Ave., Kiev 03142, Ukraine
Received April 10, 2019, published online July 26, 2019
Possible usage of magnets with partial or full compensation of the magnetic moments of different groups of spins to improve the performance of magnetic electronics devices using spin current (spintronics) are discussed. For antiferromagnets, the effects of an exchange enhancement of the spins dynamics are well known. During the past few years, the spintronics of antiferromagnets has become an independent, rapidly developing field of applied phys-ics of magnetism. In the paper, the detail analyzes of the possibility to use another class of magnetic materials, namely, ferrimagnets close to the spin compensation point, for which the noted acceler-ation effects are also present. A comparative analysis of these two classes of magnetic materials has been carried out. A study of the nonlinear spin dynamics of ferrimagnetic materials is done using a nonlinear sigma model for the antiferromagnetic vector, the difference in spin densities for two groups of spins. A simple derivation of this model is done and the real parameters for popu-lar ferrimagnets, amorphous alloys of iron group elements and rare-earth elements, are discussed. An analysis of various nonlin-ear effects of spin dynamics, from homogeneous spin oscillations in small particles till the dynamics of various solitons, domain walls, ferrimagnetic skyrmions, and vortices, is carried out. A pos-sibility of exciting such dynamic regimes by spin torque and ap-plication to ultrafast spintronics is discussed.
Key words: spintronics, ferrimagnetics, spin dynamics.