Linking insulator-to-metal transitions at zero and finite magnetic fields

Hanein, Yael; Nenadovic, N.; Shahar, D.; Shtrikman, Hadas; Yoon, Jaewon; Li, C. C.; Tsui, D. C.

doi:10.1038/23419

Cited by 41 publications

(61 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One might expect that after averaging only the largest jump, at ν = 1, may survive, and will be replaced by a smooth rapid increase. This has indeed been seen experimentally [2]. Fig.…”

Section: (7)supporting

confidence: 71%

“…One of the intriguing experimental findings [2] is that this zero-magnetic-field "transition" is continuously connected with the integer quantum Hall transition. In previous publications [3] I presented a simple non-interacting electron model, combining local quantum transport and global classical percolation, which treated the zero field transition and the quantum Hall transition on the same footing.…”

mentioning

confidence: 99%

See 1 more Smart Citation

From the zero-field metal-insulator transition in two dimensions to the quantum Hall transition: A percolation-effective-medium theory

Meir

2001

Phys. Rev. B

View full text Add to dashboard Cite

Effective-medium theory is applied to the percolation description of the metal-insulator transition in two dimensions with emphasis on the continuous connection between the zero-magnetic-field transition and the quantum Hall transition. In this model the system consists of puddles connected via saddle points, and there is loss of quantum coherence inside the puddles. The effective conductance of the network is calculated using appropriate integration over the distribution of conductances, leading to a determination of the magnetic field dependence of the critical density. Excellent quantitative agreement is obtained with the experimental data, which allows an estimate of the puddle physical parameters.PACS numbers: 71.30.+h,73.40.Hm,72.15.Rn, Extensive experimental and theoretical effort has been invested in the attempt to understand and characterize the observation of metallic-like behavior in two dimensions [1]. One of the intriguing experimental findings [2] is that this zero-magnetic-field "transition" is continuously connected with the integer quantum Hall transition. In previous publications [3] I presented a simple non-interacting electron model, combining local quantum transport and global classical percolation, which treated the zero field transition and the quantum Hall transition on the same footing. Numerical calculations showed behavior qualitatively similar to that observed experimentally. In the present paper I present an analytic approach, based on the effective-medium theory of percolation [4], that allows quantitative comparison with the experiment. This comparison also allows determination of physical properties of the underlying electronic state. The implications on transport in the quantum Hall regime due to this continuous connection to the zero-field transition are discussed and shown to be in agreement with experimental observations in the quantum Hall regime.The model is based on two assumptions: (a) the potential fluctuations due to the disorder define density puddles, connected via saddle points, or quantum pointcontacts (QPCs), and (b) The electron wavefunction totally dephases in the puddles, i.e. the time the particle spends in the puddle is larger that the dephasing time. Each saddle point is characterized by its critical energy ǫ c , such that the transmission through it is given by T (ǫ) = Θ(ǫ − ǫ c ), where quantum tunneling has been neglected. Thus the conductance through each QPC is given by the Landauer formula,

show abstract

“…One might expect that after averaging only the largest jump, at ν = 1, may survive, and will be replaced by a smooth rapid increase. This has indeed been seen experimentally [2]. Fig.…”

Section: (7)supporting

confidence: 71%

mentioning

confidence: 99%

From the zero-field metal-insulator transition in two dimensions to the quantum Hall transition: A percolation-effective-medium theory

Meir

2001

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…Among these findings is the magnetic-field induced metal-insulator-transition (MIT), which shows significant similarities to the one discovered in dilute 2D electron systems [26]. As in graphite [1], in some of these 2D systems the MITs have been shown to be connected to quantum-Hall-insulator-transitions at high magnetic fields [27]. After these experimental observations and the first theoretical prediction for the QHE in graphite [28], which was followed by further developed theoretical studies [29,30], the occurrence of quantumHall-states in graphite was already expected.…”

mentioning

confidence: 84%

Integer quantum Hall effect in graphite

Kempa

Esquinazi

Kopelevich

2006

Solid State Communications

View full text Add to dashboard Cite

We present Hall effect measurements on highly oriented pyrolytic graphite that indicate the occurrence of the integer quantum-Hall-effect. The evidence is given by the observation of regular plateau-like structures in the field dependence of the transverse conductivity obtained in van der Pauw configuration. Measurements with the Corbino-disk configuration support this result and indicate that the quasi-linear and non-saturating longitudinal magnetoresistance in graphite is governed by the Hall effect in agreement with a recent theoretical model for disordered semiconductors. Recent experimental [1,2,3,4,5,6] and theoretical [7,8,9] work demonstrates the occurrence of correlated phenomena in the electron system of graphite, indicating that the classical view of the physics of its magnetotransport properties is not adequate. Besides, the quantum Hall effect (QHE) [1] as well as evidence for Dirac fermions (massless particles due to the linear dispersion relation) [5] have been reported for bulk samples of highly oriented pyrolytic graphite of high quality. Recently published results obtained on bulk graphite [10,11], a few layers thick graphite [12], and in graphene (single graphite layer) [13,14] have confirmed both observations and showed that in graphene the QHE is anomalous in that the contribution of the Dirac fermions makes the plateaus to occur at half-integer filling factors. Certainly, the understanding of the electronic properties of graphite is necessary for the development of advanced technology of the graphite-related nanomaterials.

show abstract

“…The current observation is consistent with the studies that have been done in the past for the 2DHS through transport measurements. 18,19 This implies that for the 2DHS there is indeed a metallic regime (as shown) in the thermodynamic limit which does not exist in the phase diagrams for the 2DES. We would like to note here the data in Fig.…”

Section: 6mentioning

confidence: 99%

Thermodynamic Signature of a Two-Dimensional Metal-Insulator Transition

2000

View full text Add to dashboard Cite

We present a study of the compressibility, κ, of a two-dimensional hole system which exhibits a metal-insulator phase transition at zero magnetic field. It has been observed that dκ dp changes sign at the critical density for the metal-insulator transition. Measurements also indicate that the insulating phase is incompressible for all values of B. Finally, we show how the phase transition evolves as the magnetic field is varied and construct a phase diagram in the density-magnetic field plane for this system. 73.40.Hm, 71.30+h, 72.20.My Recently, we are seeing a growing body of experimental evidence supporting a metal-insulator quantum phase transition in a number of two-dimensional electron 1 and hole systems 2 where coulomb interactions are strong and particle mobility is quite high. These experiments are of interest because of the prevailing theory of noninteracting particle systems in two dimensions which states that only insulating behavior should be seen at all densities for even the smallest amount of disorder in the system.3 In order to further understand the nature of the unusual phase transition, it is important to study the thermodynamic properties near the transition. One particular question is whether there is any signature for the phase transition in a thermodynamic measurement. Theoretically, within the framework of Fermi liquid, one does not expect any qualitative change in the thermodynamic properties.4 On the other hand, recent theories for strong interacting systems 5,6 have predicted that there should be profound consequences in thermodynamic measurements.In this paper, we address this issue by presenting a measurement of one of the fundamental thermodynamic quantities: the thermodynamic density of states (or equivalently, the compressibility) of a strongly interacting two-dimensional hole system (2DHS). We report evidence that the compressibility measurement indeed provides an unambiguous signature for the metalinsulator transition (MIT). The insulating phase is incompressible. Furthermore, we show that the phase transition at B = 0 is intimately related to the quantum Hall state to insulator transition for the lowest Landau level in a finite magnetic field.Traditionally, to obtain the density of states (DOS) or the compressibility of a 2D electron system, capacitance between the 2D electrons and the gate is measured. 7-10This capacitance can be modeled as the geometrical capacitance in series with a quantum capacitance. The quantum capacitance per unit area c q is related to the DOS dn dµ by c q = e 2 dn dµ , or to κ by c q = n 2 e 2 κ where µ is the chemical potential and n is the carrier density. One major drawback of this method is that, in the low magnetic field limit, the quantum capacitance is much larger than the geometric capacitance. For two capacitors in series, small uncertainty in the geometric capacitance can lead to a large quantitative error (even a sign error) in the extracted κ. In a pioneering experiment by Eisenstein et al.11 , the penetration of the electric field thr...

show abstract

Linking insulator-to-metal transitions at zero and finite magnetic fields

Cited by 41 publications

References 24 publications

From the zero-field metal-insulator transition in two dimensions to the quantum Hall transition: A percolation-effective-medium theory

From the zero-field metal-insulator transition in two dimensions to the quantum Hall transition: A percolation-effective-medium theory

Integer quantum Hall effect in graphite

Thermodynamic Signature of a Two-Dimensional Metal-Insulator Transition

Contact Info

Product

Resources

About