Magnetic-field-induced insulator-quantum Hall-insulator transition in a disordered two-dimensional electron gas

Hughes, R. J. F.; Nicholls, J.E.; Frost, J. E. F.; Linfield, E. H.; Pepper, M.; Ford, C. J. B.; Ritchie, D. A.; Jones, G. A. C.; Kogan, Eugene; Kaveh, M.

doi:10.1088/0953-8984/6/25/014

Cited by 78 publications

(66 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The transition B, B c = 10.62 T (ν c = 0.58), where ρ xx is T -independent, is indicated by the dotted vertical line. The value of ρ xx at the transition, ρ xxc = 0.77 h/e 2 , is in agreement with previous experimental results where ρ xxc ∼ h/e 2 [18,19,20,21]. The ρ xx fluctuations here are much larger than at low-B, and have an amplitude as high as 2,840 Ω on the insulating side.…”

supporting

confidence: 91%

Observation of a Quantized Hall Resistivity in the Presence of Mesoscopic Fluctuations

Peled

Shahar²,

Chen³

et al. 2003

Phys. Rev. Lett.

View full text Add to dashboard Cite

We present an experimental study of mesoscopic, two-dimensional electronic systems at high magnetic fields. Our samples, prepared from a low-mobility InGaAs/InAlAs wafer, exhibit reproducible, sample specific, resistance fluctuations. Focusing on the lowest Landau level we find that, while the diagonal resistivity displays strong fluctuations, the Hall resistivity is free of fluctuations and remains quantized at its ν = 1 value, h/e 2 . This is true also in the insulating phase that terminates the quantum Hall series. These results extend the validity of the semicircle law of conductivity in the quantum Hall effect to the mesoscopic regime.PACS numbers: 71.30.+h, 72.80.Sk, For small, mesoscopic samples, the conductivity in the Quantum Hall (QH) regime exhibits reproducible, sample specific, fluctuations [1,2,3,4,5,6,7,8,9,10,11,12]. Although quite interesting by themselves, the greatest benefit in studying these fluctuations is that they can provide clues to the nature of the mechanism responsible for conduction in the QH regime.There are several known mechanisms that can lead to such fluctuations. Fluctuations as a result of the modification of the interference between many possible electron paths across the sample are at the heart of the theory of Universal Conductance Fluctuations (UCF) [13]. Although this theory is not expected to be valid at high magnetic fields (B), modified UCF theories have been suggested [14,15] to take into account the influence of B on the electron trajectories, and several experiments were interpreted in terms of UCF at high B [2,3].A different point of view has been suggested by two recent experimental studies: Cobden et al. [4], and Machida et al. [5] have found that in the QH regime fluctuation patterns follow straight lines in the magnetic field-carrier-density plane. These lines appear to be parallel to integer Landau level (LL) filling-factor lines. These results were attributed to charging of electron puddles in the sample [4], or to changes in a compressiblestrip network configuration [5].Another possible source of fluctuations, expected to dominate when B is high enough such that only a small number of LL are occupied, is resonant tunneling [16]. In this process fluctuations arise when an electron scatters from one edge of the sample to the other through a bulk impurity. This model was found to be consistent with observed high-B fluctuations [6], and has been used in measurements of fractional charge [7,8]. Applying this model to the case when only the lowest LL is occupied, Jain and Kivelson [16] argued that the fluctuations will be limited to the diagonal resistivity, ρ xx , leaving the Hall resistivity, ρ xy , quantized. This conjecture was contended by Bütikker [17]. Experiments have so far shown that fluctuations in ρ xx are accompanied by fluctuations in ρ xy [1,2,6], although these experiments were limited to relatively lower B's, where more than one LL participates in the conduction (ν ≥ 2).In this letter we report on an experimental study of the resistivity of meso...

show abstract

supporting

confidence: 91%

Observation of a Quantized Hall Resistivity in the Presence of Mesoscopic Fluctuations

Peled

Shahar²,

Chen³

et al. 2003

Phys. Rev. Lett.

View full text Add to dashboard Cite

show abstract

“…Despite considerable work in the literature relating to spin effects in the IQHE, it remains unclear whether this type of termination is a phase transition. The interest is renewed recently when the effect of spin on the quantum Hall liquid-insulator transition has became a subject of debate [3][4][5][6][7] . It was observed experimentally in the GaAs based systems that there is a direct phase transition from an insulator with σ xy = 0 to a ν = 2 quantum Hall liquid with σ xy = 2e 2 /h (will be called the 0-2 transition) [3][4][5] .…”

mentioning

confidence: 99%

Termination of the spin-resolved integer quantum Hall effect

et al. 1997

View full text Add to dashboard Cite

We report a magnetotransport study of the termination of the spinresolved integer quantum Hall effect by controlled disorder in a gated GaAs/Al x GaAs 1−x heterostructure. We have found that, for a given N th Landau level, the difference in filling factors of a pair of spin-split resistivity peaks δν N = |ν N ↑ -ν N ↓ | changes rapidly from one to zero near a critical density n c . Scaling analysis shows that δν N collapses onto a single curve independent of N when plotted against the parameter (n − n c )/n c for five Landau levels. The effect of increasing the Zeeman energy is also examined by tilting the direction of magnetic field relative to the plane of the twodimensional electron gas. Our experiment suggests that the termination of the spin-resolved quantum Hall effect is a phase transition. PACS number(s):Typeset using REVT E X 1

show abstract

“…The above dependence E n (B), treated as a dependence of ρ 0 xx = σ −1 0 versus the inverse filling factor is, in fact, an essential constituent of the global phase diagram of the quantum Hall effect (QHE) introduced by Kivelson, Lee, and Zhang [9] (namely, an integer QHE part of this diagram). Recent experiments [10][11][12][13], in which insulator -quantum Hall conductorinsulator transition was observed with increasing magnetic field, were interpreted in terms of the global phase diagram [9]. Using Fig.…”

mentioning

confidence: 99%

“…Using Fig. 1 the interpretation presented in [10,12,13] can be reformulated as follows. If the Fermi level at zero field lies within some certain range, as shown in Fig.…”

mentioning

confidence: 99%

Weak Levitation of 2D Delocalized States in a Magnetic Field

1995

Phys. Rev. Lett.

View full text Add to dashboard Cite

The deviation of the energy position of a delocalized state from the center of Landau level is studied in the framework of the Chalker-Coddington model.It is demonstrated that introducing a weak Landau level mixing results in a shift of the delocalized state up in energy. The mechanism of a levitation is a neighboring -Landau level -assisted resonant tunneling which "shunts" the saddle-points. The magnitude of levitation is shown to be independent of the Landau level number.

show abstract

Magnetic-field-induced insulator-quantum Hall-insulator transition in a disordered two-dimensional electron gas

Cited by 78 publications

References 18 publications

Observation of a Quantized Hall Resistivity in the Presence of Mesoscopic Fluctuations

Observation of a Quantized Hall Resistivity in the Presence of Mesoscopic Fluctuations

Termination of the spin-resolved integer quantum Hall effect

Weak Levitation of 2D Delocalized States in a Magnetic Field

Contact Info

Product

Resources

About