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On the direct insulator-quantum Hall transition in two-dimensional electron systems in the vicinity of nanoscaled scatterers.

Liang CT, Lin LH, Kuang Yoa C, Lo ST, Wang YT, Lou DS, Kim GH, Yuan-Huei C, Ochiai Y, Aoki N, Chen JC, Lin Y, Chun-Feng H, Lin SD, Ritchie DA - Nanoscale Res Lett (2011)

Bottom Line: Such a transition has been attracting a great deal of both experimental and theoretical interests.In this study, we present three different two-dimensional electron systems (2DESs) which are in the vicinity of nanoscaled scatterers.All these three devices exhibit a direct I-QH transition, and the transport properties under different nanaoscaled scatterers are discussed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, National Taiwan University, Taipei 106, Taiwan. ctliang@phys.ntu.edu.tw.

ABSTRACT
A direct insulator-quantum Hall (I-QH) transition corresponds to a crossover/transition from the insulating regime to a high Landau level filling factor ν > 2 QH state. Such a transition has been attracting a great deal of both experimental and theoretical interests. In this study, we present three different two-dimensional electron systems (2DESs) which are in the vicinity of nanoscaled scatterers. All these three devices exhibit a direct I-QH transition, and the transport properties under different nanaoscaled scatterers are discussed.

No MeSH data available.


ρxx(B) at various temperatures ranging from 0.28 to 20 K (Sample B).
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Figure 4: ρxx(B) at various temperatures ranging from 0.28 to 20 K (Sample B).

Mentions: As mentioned earlier, a GaN-based electron system can be affected by nanoscaled dislocation and impurities. It is therefore interesting to study such a system. Figure 4 shows magnetoresistance measurements on Sample B as a function of magnetic field at different temperatures. The data deviate slightly from the expected symmetric behavior, i.e., R(B) = R(-B). The reason for this could be due to slight misalignment of the voltage probes. Nevertheless, it can be seen that at Bc = 11 Tand -Bc = -11 T, the measured resistances are approximately temperature independent. The corresponding Landau level filling factor is about 50 in this case. Therefore, a direct 0-50 transition has been observed. Note that even at the highest attainable field of approximately 15 T, there is no sign of resistance oscillations due to the moderate mobility of our GaN system. Therefore, the experimental results of this study clearly demonstrate that the observed direct I-QH transition is irrelevant to Landau quantization. Therefore, the onset of Landau quantization does not necessarily accompany the direct I-QH transition, inconsistent with Huckestein's model [20].


On the direct insulator-quantum Hall transition in two-dimensional electron systems in the vicinity of nanoscaled scatterers.

Liang CT, Lin LH, Kuang Yoa C, Lo ST, Wang YT, Lou DS, Kim GH, Yuan-Huei C, Ochiai Y, Aoki N, Chen JC, Lin Y, Chun-Feng H, Lin SD, Ritchie DA - Nanoscale Res Lett (2011)

ρxx(B) at various temperatures ranging from 0.28 to 20 K (Sample B).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211178&req=5

Figure 4: ρxx(B) at various temperatures ranging from 0.28 to 20 K (Sample B).
Mentions: As mentioned earlier, a GaN-based electron system can be affected by nanoscaled dislocation and impurities. It is therefore interesting to study such a system. Figure 4 shows magnetoresistance measurements on Sample B as a function of magnetic field at different temperatures. The data deviate slightly from the expected symmetric behavior, i.e., R(B) = R(-B). The reason for this could be due to slight misalignment of the voltage probes. Nevertheless, it can be seen that at Bc = 11 Tand -Bc = -11 T, the measured resistances are approximately temperature independent. The corresponding Landau level filling factor is about 50 in this case. Therefore, a direct 0-50 transition has been observed. Note that even at the highest attainable field of approximately 15 T, there is no sign of resistance oscillations due to the moderate mobility of our GaN system. Therefore, the experimental results of this study clearly demonstrate that the observed direct I-QH transition is irrelevant to Landau quantization. Therefore, the onset of Landau quantization does not necessarily accompany the direct I-QH transition, inconsistent with Huckestein's model [20].

Bottom Line: Such a transition has been attracting a great deal of both experimental and theoretical interests.In this study, we present three different two-dimensional electron systems (2DESs) which are in the vicinity of nanoscaled scatterers.All these three devices exhibit a direct I-QH transition, and the transport properties under different nanaoscaled scatterers are discussed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, National Taiwan University, Taipei 106, Taiwan. ctliang@phys.ntu.edu.tw.

ABSTRACT
A direct insulator-quantum Hall (I-QH) transition corresponds to a crossover/transition from the insulating regime to a high Landau level filling factor ν > 2 QH state. Such a transition has been attracting a great deal of both experimental and theoretical interests. In this study, we present three different two-dimensional electron systems (2DESs) which are in the vicinity of nanoscaled scatterers. All these three devices exhibit a direct I-QH transition, and the transport properties under different nanaoscaled scatterers are discussed.

No MeSH data available.