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Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials
Published on: January 21, 2016
Experimental evidence for direct insulator-quantum Hall transition in multi-layer graphene
Chiashain Chuang1, Li-Hung Lin, Nobuyuki Aoki
1Department of Physics, National Taiwan University, Taipei 106, Taiwan. n-aoki@faculty.chiba-u.jp.
Nanoscale Research Letters
|May 8, 2013
Summary
Magnetotransport measurements reveal a direct insulator-quantum Hall (I-QH) transition in multi-layer graphene. This transition exhibits a unique quantum mobility, distinct from classical mobility, suggesting a universal 2D phenomenon.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- The insulator-quantum Hall (I-QH) transition is a key phenomenon in two-dimensional (2D) electron systems.
- Understanding the transition dynamics and associated electronic properties is crucial for developing novel electronic devices.
Purpose of the Study:
- To investigate the direct insulator-quantum Hall (I-QH) transition in multi-layer graphene.
- To determine and compare the quantum and classical mobilities at this transition.
- To assess the universality of the direct I-QH transition in 2D materials.
Main Methods:
- Magnetotransport measurements were conducted on a multi-layer graphene flake.
- Longitudinal resistivity (ρxx) and Hall resistivity (ρxy) were measured as a function of magnetic field.
- Analysis of magnetoresistivity oscillation amplitudes was used to determine quantum mobility (μq).
Main Results:
- A temperature-independent point in ρxx at the critical magnetic field (Bc) indicated the direct I-QH transition.
- Quantum mobility at the transition was found to be μqBc ≈ 0.37, significantly less than 1.
- Classical mobility (μBc) was observed to be approximately 1, with ρxx close to ρxy at Bc.
Conclusions:
- The study suggests the necessity of distinct mobility definitions for the direct I-QH transition in multi-layer graphene.
- Experimental data from graphene, alongside existing results from other material systems, supports the direct I-QH transition as a universal effect in 2D systems.
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