The anomalies of optical properties of d- and f-transition metals during magnetic transformations

Abstract

Abstract A review which covers the study of the optical response of 3d (Cr and its alloys) and 4f (Gd, Tb, Dy, Ho, Er, Tm) metals on magnetic “order-disorder” (FM-P, AFM-P) and “order-norder” (AFM-FM) phase transitions is presented. The influence of antiferromagnetic (AFM) transformations on optical properties of Cr and Cr-alloys with Mn, Fe, Co, Ru, Re is considered in detail. It is shown, that the process of formation of additional energy gaps in the AFM state is accompanied by a reduction of the number of electrons in the conduction bands. Estimates of “magnetic” gap magnitudes based on optical data are presented. The nature of band antiferromagnetism in Cr and its connection with the topology of Fermi surface is discussed. Peaks of resonance absorption in the near infrared region, observed in the optical conductivity spectra of some heavy rare earth metals are connected with quantum electron transitions between energy bands near the Fermi level split by s, d-f exchange interaction. The nature of the appearance of such peaks in AFM and FM states is analyzed taking into account specific features of the electronic structure and strong spin-orbital coupling in the rare earth metals.