Fermi-surface topology of ${\mathrm{\kappa }-(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}-\mathrm{T}\mathrm{T}\mathrm{F})\mathrm{}}_2{\mathrm{Cu}\left[\mathrm{N}\right(\mathrm{CN})\mathrm{}}_2]\mathrm{Br}$ at ambient pressure

Ambient pressure Fermi-surface measurements are reported for ${\mathrm{\kappa }-(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}-\mathrm{T}\mathrm{T}\mathrm{F})\mathrm{}}_2{\mathrm{Cu}\left[\mathrm{N}\right(\mathrm{CN})\mathrm{}}_2]\mathrm{Br}.\mathrm{}$ The single Shubnikov–de Haas frequency that is detected (3798±5 T) corresponds to 100% of the Brillouin zone and can be attributed to the β orbit that results from magnetic breakdown. From the temperature dependence of the oscillations, it appears that ${\mathrm{\kappa }-(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}-\mathrm{T}\mathrm{T}\mathrm{F})\mathrm{}}_2{\mathrm{Cu}\left[\mathrm{N}\right(\mathrm{CN})\mathrm{}}_2)\mathrm{B}\mathrm{r}$ possesses a conventional Fermi-liquid ground state, although with a short mean free path, possibly due to the presence of Cu(II) ions. The effective mass as determined from the $\beta$-orbit oscillations is $m^{*}=5.4\mathrm{}\pm {0.1m}_e.$