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

Article

关键词: 2-DIMENSIONAL HOLE GAS;    2 DIMENSIONS;    QUANTUM DIFFUSION;    SCALING THEORY;    ELECTRON-GAS;    SI MOSFETS;    PHASE;    GAAS;    B=0;    CONDUCTIVITY;   

DOI  :  10.1038/23419

来源: SCIE

【 摘 要 】

For many years, it was widely accepted(1) that electrons confined to two dimensions would adopt an insulating ground state at zero temperature and in zero magnetic field. Application of a strong perpendicular magnetic field changes this picture, resulting(2,3) in a transition from the insulating phase to a metallic quantum Hall state. Unexpectedly, an insulator-to-metal transition was recently observed(4) in high-quality two-dimensional systems at zero magnetic field on changing the charge carrier density. The mechanism underlying this transition remains unknown(5-9). Here we investigate the magnetic-field-driven transition in a two-dimensional gallium arsenide system, which also exhibits(10-12) the poorly understood zero-field transition. We find that, on increasing the carrier density, the critical magnetic field needed to produce an insulator-to-metal transition decreases continuously and becomes zero at the carrier density appropriate to the zero-field transition. Our results suggest that both the finite- and zero-magnetic field transitions share a common physical origin.

【 授权许可】

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