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Conductivity of a 2DEG in Si/SiGe heterostructure near metal- insulator transition: role of the short and long range scattering potential

Autor: Olshanetsky, E. B., Renard, V., Kvon, Z. D., Portal, J. C., Woods, N. J., Zhang, J., Harris, J. J

We report the observation of a metal-insulator transition (MIT) in a two- dimensional electron gas (2DEG) in a Si/SiGe heterostructure at zero magnetic field. On going through the MIT we observe the corresponding evolution of the magnetic field induc

Externí odkaz: http://arxiv.org/abs/cond-mat/0303269

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Phonon drag thermopower and weak localization

Autor: Miele, A., Fletcher, R., Zaremba, E., Feng, Y., Foxon, C. T., Harris, J. J.

Previous experimental work on a two-dimensional (2D) electron gas in a Si-on-sapphire device led to the conclusion that both conductivity and phonon drag thermopower $S^g$ are affected to the same relative extent by weak localization. The present pap

Externí odkaz: http://arxiv.org/abs/cond-mat/9807143

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Searches for Skyrmions in the Limit of Zero g-Factor

Autor: Leadley, D. R., Nicholas, R. J., Maude, D. K., Utjuzh, A. N., Portal, J. C., Harris, J. J., Foxon, C. T.

Energy gaps have been measured for the ferromagnetic quantum Hall effect states at v=1 and 3 in GaAs/GaAlAs heterojunctions as a function of Zeeman energy, which is reduced to zero by applying hydrostatic pressures of up to 20kbar. At large Zeeman en

Externí odkaz: http://arxiv.org/abs/cond-mat/9805357

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Critical Collapse of the Exchange Enhanced Spin Splitting in 2-D Systems

Autor: Leadley, D. R., Nicholas, R. J., Harris, J. J., Foxon, C. T.

The critical filling factor v_c where Shubnikov-de Haas oscillations become spin split is investigated for a set of GaAs-GaAlAs heterojunctions. Finite temperature magnetoresistance measurements are used to extract the value of v_c at zero temperatur

Externí odkaz: http://arxiv.org/abs/cond-mat/9805332

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Fractional Quantum Hall Effect Measurements at Zero g-Factor

Autor: Leadley, D. R., Nicholas, R. J., Maude, D. K., Utjuzh, A. N., Portal, J. C., Harris, J. J., Foxon, C. T.

Fractional quantum Hall effect energy gaps have been measured in GaAs/GaAlAs heterojunctions as a function of Zeeman energy, which is varied by applying hydrostatic pressure up to 20 kbar. The gap at v=1/3 decreases with pressure until the g-factor c

Externí odkaz: http://arxiv.org/abs/cond-mat/9706157

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Magnetotransport in a pseudomorphic GaAs/GaInAs/GaAlAs heterostructure with a Si delta-doping layer

Autor: van der Burgt, M., Karavolas, V. C., Peeters, F. M., Singleton, J., Nicholas, R. J., Herlach, F., Harris, J. J., Van Hove, M., Borghs, G.

Magnetotransport properties of a pseudomorphic GaAs/Ga0.8In0.2As/Ga0.75Al0.25As heterostructure are investigated in pulsed magnetic fields up to 50 T and at temperatures of T=1.4 K and 4.2 K. The structure studied consists of a Si delta-layer paralle

Externí odkaz: http://arxiv.org/abs/cond-mat/9508147

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Pulsed Magnetic Field Measurements of the Composite Fermion Effective Mass

Autor: Leadley, D. R., van der Burgt, M., Nicholas, R. J., Foxon, C. T., Harris, J. J.

Magnetotransport measurements of Composite Fermions (CF) are reported in 50 T pulsed magnetic fields. The CF effective mass is found to increase approximately linearly with the effective field $B^*$, in agreement with our earlier work at lower fields

Externí odkaz: http://arxiv.org/abs/cond-mat/9508059

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