Tunable insulator-quantum Hall transition in a weakly interacting two-dimensional electron system
- PDF / 1,169,444 Bytes
- 11 Pages / 595.28 x 793.7 pts Page_size
- 10 Downloads / 148 Views
NANO EXPRESS
Open Access
Tunable insulator-quantum Hall transition in a weakly interacting two-dimensional electron system Shun-Tsung Lo1, Yi-Ting Wang2, Sheng-Di Lin3, Gottfried Strasser4, Jonathan P Bird5, Yang-Fang Chen1,2 and Chi-Te Liang1,2*
Abstract We have performed low-temperature measurements on a gated two-dimensional electron system in which electron–electron (e-e) interactions are insignificant. At low magnetic fields, disorder-driven movement of the crossing of longitudinal and Hall resistivities (ρxx and ρxy) can be observed. Interestingly, by applying different gate voltages, we demonstrate that such a crossing at ρxx ~ ρxy can occur at a magnetic field higher, lower, or equal to the temperature-independent point in ρxx which corresponds to the direct insulator-quantum Hall transition. We explicitly show that ρxx ~ ρxy occurs at the inverse of the classical Drude mobility 1/μD rather than the crossing field corresponding to the insulator-quantum Hall transition. Moreover, we show that the background magnetoresistance can affect the transport properties of our device significantly. Thus, we suggest that great care must be taken when calculating the renormalized mobility caused by e-e interactions. Keywords: Hall effect; Magnetoresistance; Electrons; Direct insulator-quantum hall transition
Background At low temperatures (T), disorder and electron–electron (e-e) interactions may govern the transport properties of a two-dimensional electron system (2DES) in which electrons are confined in a layer of the nanoscale, leading to the appearance of new regimes of transport behavior [1]. In the presence of sufficiently strong disorder, a 2DES may behave as an insulator in the sense that its longitudinal resistivity (ρxx) decreases with increasing T [2]. It is useful to probe the intriguing features of this 2D insulating state by applying a magnetic field (B) perpendicular to the plane of a 2DES [2-4]. In particular, the direct transition from an insulator (I) to a high filling factor (v ≥ 3) quantum Hall (QH) state continues to attract a great deal of both experimental [5-13] and theoretical [14-16] interest. This is motivated by the relevance of this transition to the zero-field metalinsulator transition [17] and by the insight it provides on * Correspondence: [email protected] 1 Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan 2 Department of Physics, National Taiwan University, Taipei 106, Taiwan Full list of author information is available at the end of the article
the evolution of extended states at low magnetic fields. It has already been shown that the nature of the background disorder, in coexistence with e-e interactions, may influence the zero-field metallic behavior [18] and the QH plateau-plateau transitions [19,20]. However, studies focused on the direct I-QH transitions in a 2DES with different kinds of disorder are still lacking. Previously, we have studied a 2DES containing self-assembled InAs quantum dots [11], providing a predominantly short-ran
Data Loading...
