Spin Dynamics for Antiferromagnets and Ultrafast Spintronics

A brief review is given of the physical properties of antiferromagnets (AFMs) that can be used as active elements of terahertz and subterahertz range nanooscillators based on the excitation of spin oscillations by spin transfer torque. Possible schemes of such devices are considered. The analysis is carried out from a unified point of view on the basis of the nonlinear sigma model for the antiferromagnetic vector with regard to the magnetic symmetry of real AFMs. Specific properties of AFMs, first of all, the possibility of faster (compared to ferromagnets) spin dynamics, as well as the manifestations of antiferromagnetic ordering in galvanomagnetic and optical effects, are described. The history of the development of AFM physics is briefly discussed, first of all, those aspects of it that may be important for the practical application of AFMs, in particular, in ultrafast spintronics.