Submillimetric cyclotron resonance linewidths and electron relaxation time in copper

Abstract

For the first time submillimetric microwaves (λ<1 mm) are used to observe Azbel' Kaner cyclotron resonance in metals. The very high frequency used (typicallyF≅400 GHz) gives a large value ofωτ (typically 500) and therefore very sharp peaks. The fundamental resonance fieldH c=m * cω/e is rather high (typically 200 KG), so subharmonicsH c/n can be observed at many values ofH in the field region 0–27 KG. If relatively few electrons participate in the resonance and ifω cτ≧50 (ω c=eH/m * c,τ relaxation time) thenChambers has shown that the line shapes are independent of relaxation time while the fractional linewidthΔH/H varies as l/ωτ. For the belly orbit in pure copper the conditions of Chambers' theory are satisfied forH≧20 KG parallel to [111] axis.m * is a minimum andτ=1.8×10−10 s.