Submillimeter Spectroscopy of Weak Antiferromagnets in Magnetic Fields Up to 300 kOe

The dynamic properties of antiferromaggets with Dzyaloshinsky interaction were investigated at wavelengths 0.3- 14 mm, in magnetic fields up to 300 kOe and temperature 4.2-400 K. The problems of impurities, field induced phase transitions, types of spin oscillation, etc., for different types of antiferromagnets with Dzyaloshinsky interaction are discussed. Based on the investigation results, a new approach to the physics of magnetic phenomena, using the complete rational basis of invariants and avoiding potential series expansion, has been developed.