Magnetic thaw-down and boil-off due to magneto acceptors in 2DEG

Christophe Chaubet (1) , Andre Raymond (1)

1 L2C - Laboratoire Charles Coulomb

The Quantum Hall Effect (QHE) and Shubnikov-de Haas effect are investigated experimentally using n type modulation-doped GaAs/GaAlAs quantum wells (QWs) additionally doped in the well with beryllium acceptor atoms. It is presently shown that the localized magneto-acceptor (MA) states which possess discrete energies above the corresponding Landau levels (LLs) lead to two observable effects in magneto-transport: magnetic thaw-down and magnetic boil-off of 2D electrons. Both effects are related to the fact that electrons occupying the localized MA states cannot conduct. Thus in the thaw-down effect the electrons fall down from the MA states to the free Landau states. This leads to a shift of the Hall plateau towards higher magnetic fields as a consequence of an increase of the 2D electron density NS. In the boil-off effect the electrons are pushed from the free Landau states to the empty MA states under high enough Hall electric field. This process has an avalanche character leading to a dramatic increase of magneto-resistance, consequence of a decrease of NS.

Domaines: Physique Quantique [quant-ph]; Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

Christophe Chaubet, Andre Raymond. Magnetic thaw-down and boil-off due to magneto acceptors in 2DEG. 31st International Conference on the Physics of Semiconductors, Jul 2012, Switzerland. pp.277, ⟨10.1063/1.4848393⟩. ⟨hal-00924060⟩