Direct Observation of the Magnetic-Breakdown Induced Quantum Interference in the Quasi-Two-Dimensional Organic Metal $\mathit{\kappa }$- $(\mathrm{BEDT}$- $\mathrm{TTF}{)}_2\mathrm{CU}(\mathrm{NCS}{)}_2$

Magneto-oscillatory behavior of the organic metal $\kappa$- $(\mathrm{BEDT}$- $\mathrm{TTF}{)}_2\mathrm{Cu}(\mathrm{NCS}{)}_2$ has been studied at temperatures above 2 K at which the thermodynamic quantum oscillations are highly suppressed due to the temperature smearing of the Fermi level. Under this condition, we directly observe kinetic oscillations with $F_{\beta }{-2F}_{\alpha }$ frequency coming from quantum interference of the electron orbits in the magnetic-breakdown regime. The extremely low effective mass of these oscillations causes a very weak temperature dependence of their amplitude, allowing up to $T\simeq 9\mathrm{K}$, the highest temperature reported for the observation of magnetic quantum oscillations in organic metals.