Studies of Skyrmions at ν=1 in the Limit of Zero g-factor. (2008)
D. R. Leadley, R. J. Nicholas, D. K. Maude, A. N. Utjuzh, J. C. Portal, J. J. Harris, ...
In a two-dimensional electron gas at ν=1 (where the filling factor ν=neh/eB measures how many Landau levels (LL) are filled) the ground state should be regarded as a ferromagnet since all the spin...
FRACTIONAL QUANTUM HALL EFFECT MEASURED IN A SPIN DEGENERATE ELECTRON GAS (2008)
D. R. Leadley, R. J. Nicholas, D. K. Maude, J. C. Portal, J. J. Harris
The influence of spin on the Fractional Quantum Hall Effect is investigated in GaAs-GaAlAs heterojunctions in a filling factor region where both spin states of the lowest Landau level are occupied....
The dependence of the Composite Fermion effective mass on carrier density and Zeeman energy (2008)
R J Nicholas, D R Leadley, M S Daly, P Gee, J Singleton, ...
Abstract. Measurements of the temperature-dependent resistivity of high-mobility GaAs/GaAlAs heterojunctions are used to measure the effective mass of Composite Fermions (CF). The CF effective mass...
Measurements of composite Skyrmions at filling factor 1/3 (2008)
D. R. Leadley, R. J. Nicholas, D. K. Maude, A. N. Utjuzh, J. C. Portal, J. J. Harris, ...
Measurements of the fractional quantum Hall effect energy gaps at high pressures are presented that provide evidence for the existence of composite Skyrmions. Just as charged spin textures known as...
Critical Collapse of the Exchange Enhanced Spin Splitting in 2-D Systems (2007)
D. R. Leadley, R. J. Nicholas, J. J. Harris, C. T. Foxon
The critical filling factor νc where Shubnikov-de Haas oscillations become spin split is investigated for a set of GaAs-GaAlAs heterojunctions. Finite temperature magnetoresistance measurements are...
Spin Lifetime in High Quality InSb Epitaxial Layers Grown on GaAs (2007)
Litvinenko, K L, Nikzad, L, Allam, J, Murdin, B N, Pidgeon, C R, Harris, J J, ...
The spin relaxation in undoped InSb films grown on GaAs has been investigated in the temperature range from 77 to 290 K. Two distinct lifetime values have been extracted, 1 and 2.5 ps, dependent on...
Spin Lifetime in InAs Epitaxial Layers Grown on GaAs (2006)
Litvinenko, K L, Murdin, B N, Allam, J, Pidgeon, C R, Zhang, T, Harris, J J, ...
We report investigation of the spin relaxation in InAs films grown on GaAs at a temperature range from 77 K to 290 K. InAs is known to have a surface accumulation layer and the depth profile of the...
Spin Relaxation by Transient Monopolar and Bipolar Optical Orientation (2006)
Murdin, B N, Litvinenko, K, Clarke, D G, Pidgeon, C R, Murzyn, P, Phillips, P J, ...
We have used two-color time-resolved spectroscopy to measure the relaxation of electron spin polarizations in a bulk semiconductor. The circularly polarized pump beam induces a polarization either by...
Tuning the Inherent Magnetoresistance of InSb Thin Films (2006)
Zhang, T, Harris, J J, Branford, W R, Bugoslavsky, Y V, Clowes, S K, Cohen, L F, ...
We have investigated the 300 K inherent magnetoresistance of undoped InSb epilayers grown on GaAs(001) by molecular-beam epitaxy. The magnetoresistance of these films can be described well using a...
High-Mobility Thin InSb Films Grown by Molecular Beam Epitaxy (2004)
Zhang, T, Clowes, S K, Debnath, M, Bennett, A, Roberts, C, Harris, J J, ...
The problem of preparing high-mobility thin InSb films is revisited for magnetoresistive and spintronic sensor applications. We introduce a growth process that significantly improves the electrical...
Olshanetsky, E. B., Renard, V., Kvon, Z. D., Portal, J. C., Woods, N. J., Zhang, 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...
Phonon drag thermopower and weak localization (1998)
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...
Searches for Skyrmions in the Limit of Zero g-Factor (1998)
Leadley, D. R., Nicholas, R. J., Maude, D. K., Utjuzh, A. N., Portal, J. C., Harris, J. J., ...
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...
Critical Collapse of the Exchange Enhanced Spin Splitting in 2-D Systems (1998)
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...
Skyrmions and composite fermions in the limit of vanishing Zeeman energy (1998)
R J Nicholas, D R Leadley, D K Maude, J C Portal, J J Harris, C T Foxon
Abstract. We describe the properties of a strongly interacting two-dimensional (2D) electron gas in high magnetic fields whose properties can be described in terms of the formation of composite...
Searches for skyrmions in the limit of zero g-factor (1998)
D R Leadley, R J Nicholas, D K Maude, A N Utjuzh, J C Portal, J J Harris, ...
Abstract. Energy gaps have been measured for the ferromagnetic quantum Hall effect states at ν = 1 and 3 in GaAs/Ga0.7Al0.3As heterojunctions as a function of Zeeman energy, which is reduced to zero...
Fractional Quantum Hall Effect Measurements at Zero g-Factor (1997)
Leadley, D. R., Nicholas, R. J., Maude, D. K., Utjuzh, A. N., Portal, J. C., Harris, J. J., ...
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...
Magneto-optical probe of two-dimensional electron liquid and solid phases (1992)
Goldys, E. M., Brown, S. A., Dunford, R. B., Davies, A. G., Newbury, R., Clark, R. G., ...
Band-gap photoluminescence (PL) is used to establish the optical signature of a GaAs-Ga1-xAlxAs heterojunction in the extreme quantum limit. The temperature and field dependence of new PL structure...