Magnetotransport

We are investiagting the magnetotransport properties in curved two-dimensional electron gases. We observe clear resistance oscillations and even negative resistances in those places of the cylindrical surface, where the magnetic field is oriented tangentially to the surface. These oscillations exist only for adiabatic transport conditions, when the electrons move without scattering over distances which are comparable to the cylinder radius [1]. A detailed analysis of the equations of motion along a cylindrical surface including the Schrödinger equation exhibit distinguished free electron states within a stripe of length L_free, which are known as snake-like orbits in the classical motion of carriers on non-trivial surfaces.

Figure 1  Longitudinal resistances ρ_ij as a function of a tangentially directed magnetic field B₀ at T = 4.2 K. The inset shows the Hall bar like wave-guide indicating the terminals under investigation. The grayed rectangular within the wave-guide indicates the free-electron stripe around B_⊥ ≅ 0.

Figure 2  √B_min and √B_max as a function of half-integer and integer values q, respectively. The inset sketches the gradient related static skin effect together with snake-like orbits in the free-electron stripe around B_⊥ = 0.
 

[1] K.-J. Friedland, R. Hey, H. Kostial, and A.Riedel,
Longitudinal-commensurable resistance oscillations in the ballistic transport of electrons on cylindrical surfaces,
Phys. Status Solidi C 5, 2850-2853 (2008).