Observation of magnetic excitons and spin waves in activation studies of a two-dimensional electron gas

Usher, A.; Nicholas, R.J.; Harris, J. J.; Foxon, C.T.

doi:10.1103/physrevb.41.1129

Cited by 196 publications

(156 citation statements)

References 30 publications

Supporting

Mentioning

117

Contrasting

Unclassified

Order By: Relevance

“…For V dwell = 0 mV, we believe the nuclei remain unpolarized, and the threshold V t ∼ 0.27 mV. This suggests that g is slightly enhanced (g* ∼ 1.5g), yet still much smaller than has been measured in bulk 2DEGs [26], where g * can be as large as 20g. We interpret the shift ∆V t between dwell plots as being the Overhauser shift.…”

Section: Experimental Results and Intepretationmentioning

confidence: 80%

“…We first note that, although our simple model of the spin-split edge explains the electron transport data rather well, it does not include the well-documented effects of exchange, which have been observed [26] to greatly increase the spin gap in bulk 2DEGs near ν = 1. These effects have been predicted to manifest themselves at the edge as well, particularly in the neighborhood of the ν = 1 incompressible strip.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Dynamic nuclear polarization at the edge of a two-dimensional electron gas

et al. 1997

View full text Add to dashboard Cite

We have used gated GaAs/AlGaAs heterostructures to explore nonlinear transport between spin-resolved Landau level (LL) edge states over a submicron region of two-dimensional electron gas (2DEG). The current I flowing from one edge state to the other as a function of the voltage V between them shows diode-like behavior-a rapid increase in I above a well-defined threshold Vt under forward bias, and a slower increase in I under reverse bias. In these measurements, a pronounced influence of a current-induced nuclear spin polarization on the spin splitting is observed, and supported by a series of NMR experiments. We conclude that the hyperfine interaction plays an important role in determining the electronic properties at the edge of a 2DEG.

show abstract

Section: Experimental Results and Intepretationmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Dynamic nuclear polarization at the edge of a two-dimensional electron gas

et al. 1997

View full text Add to dashboard Cite

show abstract

“…The splittings of the 2D electron system subjected to a perpendicular magnetic field is usually expressed as a sum of the electron spin Zeeman and the electron-electron Coulomb energies: the theoretical gap include the inclusion of finite z extent, the influence of disorder, and well-to-well variation in electron density in multiple quantum well samples such as EA-124. [12]. Under our experimental conditions, the "spin gap" measured by thermal activation of xx R is much greater than the Zeeman gap corresponding to ESR transitions induced by a spatially uniform (relative to the space scale of the e-e interaction) microwave field.…”

Section: Discussionmentioning

confidence: 83%

Temperature dependence and mechanism of electrically detected ESR at theν=1filling factor of a two-dimensional electron system

et al. 2003

View full text Add to dashboard Cite

Electrically detected electron spin resonance (EDESR) signals were acquired as a function of temperature in the 0.3-4.2 K temperature range in a AlGaAs/GaAs multiple quantum well sample at the 1 ν = filling factor at 5.7 T. In the particular sample studied, the line width is approximately temperature independent, while the amplitude exhibits a maximum at about 2.2 K and vanishes with increased or decreased temperature. To explain the observed temperature dependence of the signal amplitude, the signal amplitude temperature dependence is calculated assuming a model based on heating. The model ascribes the resonant absorption of microwave power of the 2DES to the uniform mode of the electron spin magnetization where the elementary spin excitations at filling factor 1 ν = are taken to be spin waves, while the short wavelength spin wave modes serve as a heat sink for the absorbed energy. Due to the finite thermal conductance to the surroundings, the temperature of the 2DES spin wave system is increased, resulting in a thermal activation of the longitudinal magnetoconductance. The proposed heating model correctly predicts the location of the maximum in the experimentally observed temperature dependence of the EDESR amplitude. It also correctly predicts that the signal should vanish as the temperature is increased or decreased. The results of the present study demonstrate how experimental EDESR studies can, under appropriate conditions, provide data that can be used to discriminate between competing theories for the magnetic ordering and magnetic excitations of a 2DES in the regime of the quantum Hall effect.Introduction.

show abstract

“…This yields g*ϳ4.8, enhanced by some 11 times compared with its bare value, but still somewhat lower than the value of 7.3 reported in activated transport studies of exchange enhancement. 33 However if we follow the suggestion of that study that the energy gap at even filling factors is also enhanced, by about 33% in samples of similar mobilities to ours, then we estimate g* to be 6.4.…”

Section: Odd Filling Factorsmentioning

confidence: 99%

Magnetization measurements of high-mobility two-dimensional electron gases

et al. 2003

Self Cite

View full text Add to dashboard Cite

De Haas-van Alphen ͑dHvA͒ oscillations are observed for Landau levels ͑LLs͒ with filling factors between 4 and 52, at temperatures in the range 50 mK to 1 K, in experiments on high-mobility GaAs/͑Al, Ga͒As heterojunctions. The oscillations become sawtooth-shaped at low filling factors, and theoretical fits to the data, assuming the two-dimensional electron gas to be a non-interacting Fermi system, show the shape of LLs to be close to a ␦ function. The small residual width ͑ϳ0.4 meV or less͒ fits equally well to either a Gaussian or a Lorentzian density-of-states model. In almost all cases, a constant background density of states has to be included to obtain a satisfactory fit. Weak odd-filling-factor dHvA peaks are detected at high fields, from which a g-factor enhancement of 15 can be inferred. Comparison of the scattering time derived from the fits before and after illumination, with the momentum relaxation time derived from transport, reveals a counterintuitive behavior in the bulk-modulation-doped sample.

show abstract

Observation of magnetic excitons and spin waves in activation studies of a two-dimensional electron gas

Cited by 196 publications

References 30 publications

Dynamic nuclear polarization at the edge of a two-dimensional electron gas

Dynamic nuclear polarization at the edge of a two-dimensional electron gas

Temperature dependence and mechanism of electrically detected ESR at theν=1filling factor of a two-dimensional electron system

Magnetization measurements of high-mobility two-dimensional electron gases

Contact Info

Product

Resources

About