Microwave Rectification at the Boundary between Two-Dimensional Electron Systems

Rectification of microwave radiation (20-40 GHz) by a line boundary between two two-dimensional metals on a silicon surface was observed and investigated at different temperatures, in-plane magnetic fields and microwave powers. The rectified voltage $V_{dc}$ is generated whenever the electron densities $n_{1,2}$ of the two metals are different, changing polarity at $n_1 approx n_2$. Very strong nonlinear response is found when one of the two 2D metals is close to the electron density corresponding to the reported magnetic instability in this system.