Microwave-assisted transport through a quantum dot (2009)
P L Mceuen, L P Kouwenhoven, S Jauhar, J Orenstein, K Mccormick, D Dixon, ...
Abstract. We present results on microwave-assisted transport through quantum dots. First, the important energy/frequency scales are discussed. Then, measurements of the current versus gate voltage...
Haigh, J A, Rushforth, A W, King, C S, Edmonds, K W, Campion, R P, Foxon, C T, ...
We demonstrate a simple, low cost, magneto-transport method for rapidly characterizing the magnetic anisotropy and anisotropic magneto-resistance (AMR) of ferromagnetic devices with uniaxial magnetic...
Manipulation of the magnetic configuration of (Ga,Mn)As nanostructures (2009)
Haigh, J. A., Wang, M., Rushforth, A. W., Ahmad, E., Edmonds, K. W., Campion, R. P., ...
We have studied the magnetic reversal of L-shaped nanostructures fabricated from (Ga,Mn)As. The strain relaxation due to the lithographic patterning results in each arm having a uniaxial magnetic...
Toward a low-voltage multiferroic transistor: Magnetic (Ga,Mn)As under ferroelectric control (2009)
Riester, S.W.E., Stolichnov, I., Trodahl, H.J., Setter, N., Rushforth, A.W., Edmonds, K.W., ...
The persistent field effect control of ferromagnetism in a diluted magnetic semiconductor by low-voltage polarizing pulses is demonstrated in a ferroelectric gate field effect transistor...
Achieving High Curie Temperature in (Ga,Mn)As (2008)
Wang, M, Campion, R P, Rushforth, A W, Edmonds, K W, Foxon, C T, Gallagher, B L
We study the effects of growth temperature, Ga:As ratio and post-growth annealing procedure on the Curie temperature, Tc, of (Ga,Mn)As layers grown by molecular beam epitaxy. We achieve the highest...
Molecular Beam Epitaxy grown (Ga,Mn)(As,P) with perpendicular to plane magnetic easy axis (2008)
Rushforth, A W, Wang, M, Farley, N R S, Campion, R C, Edmonds, K W, Staddon, C R, ...
We present an experimental investigation of the magnetic, electrical and structural properties of Ga0.94Mn0.06As1-yPy layers grown by molecular beam epitaxy on GaAs substrates for y less than or...
Wang, K. Y., Irvine, A. C., Campion, R. P., Foxon, C. T., Wunderlich, J., Williams, D. A., ...
We have studied current-driven domain wall motion in modified Ga_0.95Mn_0.05As Hall bar structures with perpendicular anisotropy by using spatially resolved Polar Magneto-Optical Kerr Effect...
Wang, K Y, Irvine, A C, Wunderlich, J, Edmonds, K W, Rushforth, A W, Campion, R P, ...
We investigate the anisotropy of magnetic reversal and current-driven domain wall motion in annealed Ga_0.95Mn_0.05As thin films and Hall bar devices with perpendicular magnetic anisotropy. Hall bars...
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...
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...
Rushforth, A. W., De Ranieri, E., Zemen, J., Wunderlich, J., Edmonds, K. W., King, C. S., ...
We demonstrate dynamic voltage control of the magnetic anisotropy of a (Ga,Mn)As device bonded to a piezoelectric transducer. The application of a uniaxial strain leads to a large reorientation of...
Valence band orbital polarization in III-V ferromagnetic semiconductors (2008)
Freeman, A. A., Edmonds, K. W., Campion, R. P., Farley, N. R. S., Rushforth, A. W., ...
The element-specific technique of x-ray magnetic circular dichroism (XMCD) is used to directly determine the magnitude and character of the valence band orbital magnetic moments in (III,Mn)As...
The Origin and Control of the Sources of AMR in (Ga,Mn)As Devices (2007)
Rushforth, A. W., Výborný, K., King, C. S., Edmonds, K. W., Campion, R. P., Foxon, C. T., ...
We present details of our experimental and theoretical study of the components of the anisotropic magnetoresistance (AMR) in (Ga,Mn)As. We develop experimental methods to yield directly the...
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...
Wunderlich, J., Irvine, A. C., Zemen, J., Holy, V., Rushforth, A. W., De Ranieri, E., ...
The large saturation magnetization in conventional dense moment ferromagnets offers flexible means of manipulating the ordered state through demagnetizing shape anisotropy fields but these dipolar...
Anisotropic Magnetoresistance components in (Ga,Mn)As (2007)
Rushforth, A. W., Výborný, K., King, C. S., Edmonds, K. W., Campion, R. P., Foxon, C. T., ...
Our experimental and theoretical study of the non-crystalline and crystalline components of the anisotropic magnetoresistance (AMR) in (Ga,Mn)As is aimed at exploring the basic physical aspects of...
AMR and magnetometry studies of ultra thin GaMnAs films (2006)
Rushforth, A. W., Giddings, A. D., Edmonds, K. W., Campion, R. P., Foxon, C. T., Gallagher, B. L.
We have measured the Anisotropic Magnetoresistance (AMR) of ultra thin (5nm) Ga(0.95)Mn(0.05)As films. We find that the sign of the AMR can be positive or negative, which may depend on the direction...
Magnetic domain structure and magnetization reversal in (311)B Ga0.91Mn0.09As films (2006)
Pross, A., Bending, S. J., Wang, K. Y., Edmonds, K. W., Campion, R. P., Foxon, C. T., ...
Thermo-Electric Properties of Quantum Point Contacts (2005)
Van Houten, H., Molenkamp, L. W., Beenakker, C. W. J., Foxon, C. T.
I. Introduction II. Theoretical background (Landauer-Buttiker formalism of thermo-electricity, Quantum point contacts as ideal electron waveguides, Saddle-shaped potential) III. Experiments...
Large tunneling anisotropic magnetoresistance in (Ga,Mn)As nanoconstrictions (2004)
Giddings, A. D., Khalid, M. N., Wunderlich, J., Yasin, S., Campion, R. P., Edmonds, K. W., ...
We report a large tunneling anisotropic magnetoresistance (TAMR) in a thin (Ga,Mn)As epilayer with lateral nanoconstrictions. The observation establishes the generic nature of this effect, which...
Influence of low temperature annealing on the micromagnetic structure of GaMnAs films (2004)
Pross, A., Bending, S., Edmonds, K., Campion, R. P., Foxon, C. T., Gallagher, B.
Magnetic domain imaging of ferromagnetic GaMnAs films (2004)
Pross, A., Bending, S., Edmonds, K., Campion, R. P., Foxon, C. T., Gallagher, B.
DC-transport properties of ferromagnetic (Ga,Mn)As semiconductors (2003)
Jungwirth, T., Sinova, Jairo, Wang, K. Y., Edmonds, K. W., Campion, R. P., Gallagher, B. L., ...
We study the dc transport properties of (Ga,Mn)As diluted magnetic semiconductors with Mn concentration varying from 1.5% to 8%. Both diagonal and Hall components of the conductivity tensor are...
Anisotropic Magnetoresistance in GaMnAs films (2002)
Wang, K. Y., Edmonds, K. W., Campion, R. P., Zhao, L. X., Neumann, A. C., Foxon, C. T., ...
The magnetoresistance in a series of Ga1-xMnxAs samples with 0.2 =< x =< 0.8 have been measured for three mutually orthogonal orientations of the external magnetic field. The anisotropy...
The Hall effect and hole densities in high Tc GaMnAs thin films (2002)
Edmonds, K. W., Wang, K. Y., Campion, R. P., Neumann, A. C., Foxon, C. T., Gallagher, B. L., ...
By studying the Hall effect in a series of low resistivity Ga1-xMnxAs samples, accurate values for the hole density p, Mn concentration x, and Curie temperature Tc are obtained over the range 0.015=
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...