Slow Oscillations of Magnetoresistance in Quasi-Two-Dimensional Metals

Slow oscillations of the interlayer magnetoresistance observed in the layered organic metal $\beta \mathrm{\text{−}}(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\mathrm{\text{−}}\mathrm{T}\mathrm{T}\mathrm{F}{)}_2{\mathrm{I}\mathrm{B}\mathrm{r}}_2$ are shown to originate from the slight warping of its Fermi surface rather than from independent small cyclotron orbits. Unlike the usual Shubnikov–de Haas effect, these oscillations are not affected by the temperature smearing of the Fermi distribution and can therefore become dominant at high enough temperatures. We suggest that the slow oscillations are a general feature of clean quasi-two-dimensional metals and discuss possible applications of the phenomenon.

Figure 1

Interlayer resistance (a) and oscillating part of magnetic torque (b) of $\beta \mathrm{\text{−}}(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\mathrm{\text{−}}\mathrm{T}\mathrm{T}\mathrm{F}{)}_2{\mathrm{I}\mathrm{B}\mathrm{r}}_2$ versus magnetic field at $\theta \approx -15°$. The curves at different temperatures are offset for clarity.

Figure 2

Angular dependencies of the frequency of the slow oscillations (a) and background resistance at $B=14\mathrm{T}$, $T=0.44\mathrm{K}$ (b). Lines are guides for the eye.

Figure 3

Amplitudes of the fast (a) and slow (b) oscillations normalized to the background resistance plotted versus inverse magnetic field at $T=0.44\mathrm{K}$. The lines are fits to Eq. (4).