Floquet scattering theory of negative magneto-conductance of 2DEG under   microwave radiation
  We develop a theory of magneto-transport properties of two-dimensional electron gas in cylindrical geometry where finite bias and microwave are locally applied. By invesitgating the Landauer conductance based on Floquet theory, we obtain the conductance without perturbation analysis. We show that the dc conductance becomes negative when dc electric field is applied inside the 2DEG with sufficient microwave power. A positive sign of the current is restored by increasing dc bias. We analyze the radiation induced non-equilibrium distribution function with respect to the frequency of the applied microwave. 
Kang-Hun Ahn (Chungnam National Univ., Korea)