arXiv subjects

De-Cheng Tian

Publications and source records attributed to De-Cheng Tian.

3 recordsLinked to original sources

arXiv2005

Possible existence of a band of extended states induced by inter-Landau-band mixing in quantum Hall system

The mixing of states with {\it opposite chirality} in quantum Hall system is shown to have delocalization effect. It is possible that extended states may form bands because of this mixing, as is shown through a numerical calculation on a two-channel network model. Based on this result, a new phase diagram with a narrow {\it metallic} phase separating two adjacent QH phases and/or separating a QH phase from the insulating phase is proposed. The data from recent non-scaling experiments is reanalyzed and shown that they seem to be {\it consistent} with the new phase diagram. However, due to finite-size effects, further study on large system size is still needed to conclude whether there are extended state bands in thermodynamic limit.

cond-mat.mes-hall↗

arXiv2003

The effect of inter-Landau-band mixing on extended states in quantum Hall system

The effect of inter-Landau-band mixing on electron localization in an integer quantum Hall system is studied. We find that mixing of localized states with {\it opposite chirality} tends to delocalize the states. This delocalization effect survives the quantum treatment. Extended states form bands because of this mixing, as we show through a numerical calculation on a two-channel network model. Based on this result, we propose a new phase diagram with a narrow {\it metallic} phase that separates any neighboring QH phases from each other and also separates each of them from the insulating phase. We reanalyzed the data from recent non-scaling experiments, and show that they are {\it consistent} with our theory.

cond-mat.mes-hall↗

arXiv2001

A metallic phase in quantum Hall systems

The electronic eigenstates of a quantum Hall (QH) system are chiral states. Strong inter-Landau-band mixings among these states can occur when the bandwidth is comparable to the spacing of two adjacent Landau bands. We show that mixing of localized states with opposite chirality can delocalize electronic states. Based on numerical results, we propose the existence of a metallic phase between two adjacent QH phases and between a QH phase and the insulating phase. This result is consistent with non-scaling behaviors observed in recent experiments on quantum-Hall-liquid-to-insulator transition.

cond-mat.mes-hall↗