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.
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Host: Sankar Das Sarma
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