Figure 1

(Color online) (a) In plane Fermi-surface of $\kappa \text{−}{\left(\mathrm{BEDT}\text{−}\mathrm{TTF}\right)}_2\mathrm{Cu}{\left(\mathrm{NCS}\right)}_2$, showing the closed Q2D pockets (blue), the open Q1D sheets (red), and the Brillouin zone boundary (black). The dotted lines show the possible semiclassical paths between the Q1D and Q2D Fermi-surface sections at the zone boundary taken by a quasiparticle on the breakdown $\beta$ orbit. (b) Shubnikov–de Haas oscillations observed in two $\kappa \text{−}{\left(\mathrm{BEDT}\text{−}\mathrm{TTF}\right)}_2\mathrm{Cu}{\left(\mathrm{NCS}\right)}_2$ samples at $T\sim 500\mathrm{mK}$, with the magnetic field directed perpendicular to the conducting planes $(\theta =0°)$. The upper trace is for a sample at a pressure $p=9.8\pm 0.2\mathrm{kbar}$; the other is at ambient pressure. At low fields a single oscillation frequency is present corresponding to the $\alpha$ orbit. At larger fields, higher frequencies are seen, corresponding to the $\beta$ orbit and other magnetic breakdown orbits (Ref. 17). The $9.8\mathrm{kbar}$ data are enhanced by a factor of 5 and the curves are offset for clarity.Reuse & Permissions

Figure 2

(Color online) (a) Magnetoresistance of $\kappa \text{−}{\left(\mathrm{BEDT}\text{−}\mathrm{TTF}\right)}_2\mathrm{Cu}{\left(\mathrm{NCS}\right)}_2$ (black curve) as a function of $\tan \theta$ at $p=9.8\mathrm{kbar}$, $B=30\mathrm{T}$, $T=1.5\mathrm{K}$, and $\varphi =160°$. The positions of the BAMROs are marked with up (red) arrows and the Lebed oscillations with down (blue) arrows. Also shown are these positions as a function of oscillation index (points) from which the frequencies may be extracted. (b) Polar plot of the maximum in-plane Fermi wave vector, $k_{\Vert }^{\max }$, derived from the $\tan \theta$ oscillation frequency, as a function of $\varphi$. Blue squares are Yamaji oscillations and red circles are BAMROs. Fits of Eq. (2) to the data (dashed lines) allow the geometry of the orbits which give rise to the oscillations to be determined. The dimensions of the $\alpha$ orbit thus derived are shown (blue solid line). The error in $\varphi$ is $\pm 5°$.Reuse & Permissions

Figure 3

(Color online) Ambient-pressure angle-dependent magnetoresistance. (a) Comparison of data taken at $B=42\mathrm{T}$, $T=1.5\mathrm{K}$, and $\varphi =160°$ before (upper curve) and after (lower curve) filtering to remove the SdH oscillations. (b) Data taken at a similar $\varphi$ angle with $B=45\mathrm{T}$. Two temperatures are shown, $T=4.2\mathrm{K}$ (upper curve) and $T=10.6\mathrm{K}$. In both (a) and (b), up (red) arrows mark the BAMROs, down (blue) arrows mark the Lebed oscillations, and the curves are offset for clarity.Reuse & Permissions