Magnetooptical Studies of the Electronic Structure of Semimetals

Abstract

Magnetooptical studies provide a powerful tool for the study of the electronic structure of semimetals because of the low effective masses characteristic of this class of materials and because of the consequent ease of satisfying the conditions ω_cτ > 1 and ħω_c > kT, which are necessary requirements for the observation of resonant magnetooptical effects. The condition (ω_Cτ > 1 (where ω_c is the angular cyclotron frequency ${\omega _{\text{c}}}{\mkern 1mu} = {\mkern 1mu} {\text{eH/m}}_{\text{c}}^*{\text{c, m}}_{\text{c}}^*$ is the cyclotron effective mass and τ is the relaxation time), implies that an electron or hole complete a cyclotron orbit before being scattered. The condition ħω_c > kT implies that the characteristic magnetic energy ħω_C is large compared with thermal energies, so that distinct Landau levels can be resolved when in competition with thermal broadening effects. In fact, over the years, semimetals have provided important test materials for the development of experimental magnetooptical techniques, as well as theoretical models for quantitative analysis of the experimental results.