Sign Reversals of ac Magnetoconductance in Isolated Quantum Dots
Abstract
We have measured the electromagnetic response of micron-size isolated GaAs/GaAlAs square dots down to 16 mK by coupling them to a microresonator. Both dissipative and reactive responses exhibit a large magnetic field dependent quantum correction, with a characteristic flux scale corresponding to a flux quantum in a dot. The dissipative magnetoconductance changes sign as a function of frequency for a low density of electrons. The signal observed at a frequency below the mean level spacing corresponds to a negative magnetoconductance, in contrast to weak localization in connected systems, and becomes positive at higher frequencies. We interpret this phenomenon in relation to the energy spectrum statistics in the dots.
- Publication:
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Physical Review Letters
- Pub Date:
- June 1998
- DOI:
- 10.1103/PhysRevLett.80.4955
- arXiv:
- arXiv:cond-mat/9711171
- Bibcode:
- 1998PhRvL..80.4955N
- Keywords:
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- Condensed Matter - Mesoscale and Nanoscale Physics
- E-Print:
- 4 pages, 4 eps figures