Lucia Steinke

Metallic and insulating states at a bent quantum Hall junction

Grenoble High Magnetic Field Laboratories CNRS, 38042 Grenoble, France(Dated: February 6, 2008)A non-planar geometry for the quantum Hall (QH) effect is studied, whereby two quantum Hall(QH) systems are joined at a sharp right angle. When both facets are at equal filling factor ν thejunction hosts a channel with non-quantized conductance, dependent on ν. The state is metallic atν = 1/3, with conductance along the junction increasing as the temperature T drops. At ν = 1,2 itis strongly insulating, and at ν = 3,4 shows only weak T dependence. Upon applying a dc voltagebias along the junction, the differential conductance again shows three different behaviors. Hartreecalculations of the dispersion at the junction illustrate possible explanations, and differences fromplanar QH structures are highlighted.

Nanometer-scale sharpness in corner-overgrown heterostructures

A corner-overgrown GaAs∕AlGaAs heterostructure is investigated with transmission and scanning transmission electron microscopy, demonstrating self-limiting growth of an extremely sharp corner profile 3.5nm wide. In the AlGaAs layers, we observe self-ordered diagonal stripes, precipitating exactly at the corner, which show increased Al content measured with x-ray spectroscopy. A quantitative model for self-limited growth is adapted to the present case of faceted molecular beam epitaxial growth, and the corner sharpness is discussed in relation to quantum confined structures. We note that corner overgrowth maintains nanometer sharpness after microns of growth, allowing corner-shaped nanostructures.

Hopping conduction in strongly insulating states of a diffusive bent quantum Hall junction

Transport studies of a bent quantum Hall junction at integer filling factor

NOVEL ONE-DIMENSIONAL STATES IN A BENT QUANTUM HALL JUNCTION

\ensuremath{\nu}

Sharp quantum Hall edges: Experimental realizations of edge states without incompressible strips

show strongly insulating states

Electronic correlations and chiral, nonlocal transport in surface states of HfNiSn single crystals

(\ensuremath{\nu}=1,2)

Magnetotransport of surface states in HfNiSn single crystals

at higher fields. In this paper we analyze the strongly insulating behavior as a function of temperature

Unconventional large magnetoresistance in Cu

T

_{2-}_{x}

and dc bias

Te

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