Vanishing electrical resistance in condensed matter introduced the phenomena of superconductivity. More recently, the discovery of quantum Hall effects (QHE) stemmed from studies of zero-resistance states at low temperatures, T, and high magnetic fields, B, in the 2-Dimensional Electron System (2DES). Quantum Hall effect and superconductivity have also shown that observations of vanishing resistance in unusual settings can be a harbinger of new physics. Here, we report the observation of novel vanishing resistance states in an unexpected setting - the ultra high mobility 2DES irradiated by low energy photons, at low temperatures, in a low-magnetic-field, large-filling-factor limit.[1] It turns out that the GaAs/AlGaAs 2DES exhibits vanishing diagonal resistance, without Hall resistance quantization, at low T and low B when the specimen is excited by electromagnetic waves in the microwave and Terahertz parts of spectrum. Zero-resistance-states occur about B = 4/5 B_f and B = 4/9 B_f, where B_f = 2p f m^*/e, m^* is the electron mass, e is electron charge, and f is the EM-wave frequency, as the resistance-minima follow B = [4/(4j+1)] B_f with j=1,2,3… In this report, we illustrate the basic characteristics,[1,2] and highlight supplementary features, such as the voltage-current characteristics, and the transmission, reflection, and emission characteristics, in light of theory for this remarkable effect.

[1] R. G. Mani, J. H. Smet, K. von Klitzing, V. Narayanamurti, W. B. Johnson, and V.Umansky, Nature 420, 646 (2002); Phys. Rev. Lett. 92, 146801 (2004); R. G. Mani, V. Narayanamurti, K. von Klitzing, J. H. Smet, W. B. Johnson, and V. Umansky, Phys. Rev. B 69, 161306 (2004); Phys. Rev. B 70, 153310 (2004); R. G. Mani, Phys. Rev. B 72, 075327 (2005); Appl. Phys. Lett. 85, 4962 (2004).

[2] M. A. Zudov, R. R. Du, L. Pfeiffer, and K. West, Phys. Rev. Lett. 90, 046807 (2003).