Magnetic quantum oscillations of quasi-two-dimensional conductors with one-dimensional potential modulation

摘要

An analytic theory for the de Haas-van Alphen (dHvA) oscillations in layered conductors with a periodic one-dimensional (1D) potential within the planes is developed. The periodic modulation potential yields an additional factor I(p) in the Lifshitz-Kosevich harmonic series which modulates the dHvA oscillation amplitudes together with the standard Dingle, R_D(p), and temperature, R_T(P), factors (p is the number of harmonic). The factor I(p) oscillates as a function of the inverse magnetic field 1/B in low fields, when hω_c < < 4πσ, where ω_c is the cyclotron frequency and σ is proportional to the amplitude of the 1D modulation potential. For higher fields, when hω_c > > 4πσ the factor I(p) approaches unity. Correspondingly, the shape of the magnetization oscillations in the low-field region is distinctly nonsinusoidal. These oscillations cross over to a regular sinusoidallike or sawtooth-like shape, for high-quality 2D conductors. If the 1D modulation is strong enough to reconstruct the Fermi surface due to the mini-band effect, the factor I(p) also oscillates in very much the same way as in the above perturbative case. These oscillations originate from the magnetic breakdown probability oscillations between the open sheets and closed orbits in the reconstructed Fermi surface. In the Appendix an interference of the commensurate (Weiss) oscillations, which are classical in nature, and the quantum Shubnikov-de Haas oscillations in the magnetoresistance of 2D conductors with the 1D lateral modulation is briefly discussed.