Condensed Matter Seminar Series
Title: Radiation induced zero-resistance states in GaAs/AlGaAs devices
Thursday September 11, 1h30 pm, Room 234, Physics Building
Host: Gleb Finkelstein
We report the experimental detection of novel zero-resistance states ,
which are induced by electromagnetic wave excitation in ultra high mobility
GaAs/AlGaAs heterostructure devices including a two-dimensional electron
system. Radiation-induced vanishing-resistance states, which do not exhibit
concomitant Hall resistance quantization, are demonstrated in the large
filling factor, low magnetic field limit, at liquid helium temperatures. It
is shown that the observed resistance minima follow the series B =
[4/(4j+1)] Bf with j=1,2,., where Bf = 2pfm*/e, m* is an effective mass, e
is electron charge, and f is the radiation frequency. These
resistance-minima exhibit an activated resistance as a function of the
temperature that leads into zero-resistance states at the lowest
temperatures. The dependence of the effect is reported as a function of
experimental parameters such as the electromagnetic wave frequency, incident
power, temperature, and the current.
 R. G. Mani, J. H. Smet, K. von Klitzing, V. Narayanamurti, W. B.
Johnson, and V. Umansky, Nature 420, 646 (2002).