Magnetic breakdown and quantum interference in the quasi-two-dimensional superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2) in high magnetic fields
(1996) Journal of Physics: Condensed Matter — Vol. 8, n° 29, p. 5415-5435 (1996)
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- Abstract
- Magnetic breakdown phenomena have been investigated in the longitudinal magnetoresistance of the quasi-two-dimensional (Q2D) superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2) in magnetic fields of up to 50 T, well above the characteristic breakdown field. The material is of great interest because its relatively simple Fermi surface, consisting of a closed Q2D pocket and an open Q1D band, is almost identical to the initial hypothetical breakdown network proposed by Pippard. Two frequencies are expected to dominate the magnetoresistance oscillations: the a frequency, corresponding to orbits around the closed pocket, and the beta frequency, corresponding to the simplest classical breakdown orbit. However, a beta - alpha frequency is in fact found to be the dominant high-frequency oscillation in the magnetoresistance. Numerical simulations, employing standard theories for calculating the density of states, indicate that a significant presence of the beta - alpha frequency (forbidden in the standard theories) can result simply from the frequency-mixing effects associated with the pinning of the chemical potential in a quasi-two-dimensional system. While this effect is able to account for the previous experimental observation of beta - alpha frequency oscillations of small amplitude in the magnetization, it cannot explain why such a frequency dominates the high-field magnetotransport spectrum. Instead we have extended the numerical simulations to include a quantum interference model adapted for longitudinal magnetoresistance in a quasi-two-dimensional conductor. The modified simulations are then able to account for most of the features of the experimental magnetoresistance data.
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Harrison, N., Caulfield, J., Singleton, J., Reinders, P., Herlach, F., Hayes, W., Kurmoo, M., & Day, P. (1996). Magnetic breakdown and quantum interference in the quasi-two-dimensional superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2) in high magnetic fields. Journal of Physics: Condensed Matter, 8(29), 5415-5435. https://doi.org/10.1088/0953-8984/8/29/016 (Original work published 1996)