Condensed Matter Physics Seminar

2 p.m., Thursday, April 3, 2003
Room 1201, Physics Building

 Novel radiation induced zero-resistance states in the GaAs/AlGaAs 2-dimensional electron system

Ramesh Mani

(Harvard University)

Abstract:  We report the experimental discovery of zero-resistance-states induced by electromagnetic wave excitation in ultra high mobility GaAs/AlGaAs heterostructures at low temperatures, in the large-filling-factor, low-magnetic-field (B) limit.[1] In a magneto-transport study, minima in the diagonal resistance are found to occur at B = [4/(4j+1)] Bf, with Bf = 2pfm*/e, where j = 1,2,3, m* is the electron effective mass, e is electron charge, and f is the electromagnetic wave frequency, and, at the lowest temperatures, the deepest minima evolve into zero-resistance-states that are concomitant with a linear Hall effect. The observed vanishing resistance is linked to a radiation induced spectral gap, which is indicated by an activated resistance. The dependence of the effect is reported as a function of experimental parameters such as, for example, the electromagnetic wave frequency, incident power, and the temperature. 

R. G. Mani et al., Nature 420, 646 (2002); cond-mat/0303034.

Host:  Sankar Das Sarma
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