Magnetic Surface Levels in Cu—Observation and Analysis of Microwave Resonances and Determination of Fermi Velocities

Abstract

The resonance spectra of magnetic-field-induced surface states are studied in fields in the range 0-250 Oe at 36 GHz in high-purity Cu single crystals. Using the known Fermi-surface geometry of Cu, we identify the locations of the resonant electrons on the Fermi surface. We carefully consider the resonance line shape to interpret the observed $\frac{\mathrm{dR}}{\mathrm{dH}}$ (field derivative of the real part of the surface impedance) peak positions and determine the Fermi velocity point by point along the central zones in the (100) and (110) planes. Various types of surface perturbations and their effect on the line shapes of the resonances are discussed, together with some considerations of the effect of tipping the field out of the sample plane.