Zero Differential Resistance State in double GaAs quantum wells at high filling factors*

Differential resistance $r_{xx}$ of 2D electrons was investigated in double GaAs quantum wells placed in magnetic fields $B<0.5$ (T) at temperatures $T=1.6-4.2$ (K). Electron state with Zero Differential Resistance (ZDR) is found in finite current range at maximums of inter-subband quantum oscillations. The experiment shows that the ZDR state exists at $2R_cE_H/ \hbar \omega_c < 1/2$, where $R_c$ is electron cyclotron radius at Fermi level, $E_H$ is Hall electric field, induced by the $dc$ bias, and $\omega_c$ is cyclotron frequency.\\[4pt] [1] A.A. Bykov, E. G. Mosulev and S. A. Vitkalov, JETP Letters v92, (2010) to be published