Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 22: Transport im hohen Magnetfeld/Quanten-Hall-Effekt

HL 22.5: Talk

Tuesday, March 9, 2004, 16:15–16:30, H14

Spin structures in inhomogeneous fractional quantum Hall systems — •Karel Vyborny and Daniela Pfannkuche — I. Institute of Theoretical Physics, University of Hamburg, Jungiusstr. 9, D-20355 Hamburg, Germany

Huge longitudinal magnetoresistance effect in 2D electron systems was shown to be a way to manipulate and measure spin of the host material nuclei [1] and it can thus have important applications in the field of quantum computers. Since there are two nearly degenerate ground states of the electronic part of the system (polarized and singlet-state incompressible liquids at filling factor 2/3) it is widely believed that the effect is due to formation of domains which results into an enhanced resistance. To our best knowledge there is however no direct evidence of existence of such domains so far.

We study a finite size model of electrons in the lowest Landau level which was formerly used to study the Fractional Quantum Hall Effect (torus geometry, [2]). The system is now also subject to magnetic inhomogeneity which makes one of the ground states more favorable in one part and less favorable in another part of the system. We investigate how the system answers to various types of inhomogeneities in spin quantities and particle densities as well as in correlation functions.

[1] S. Kronmüller et al., Phys. Rev. Lett., 81, 2526 (1998), J. Smet et al., Nature, 415, 281 (2002), S. Kraus et al., Phys. Rev. Lett, 89, 266801 (2002)

[2] D. Yoshioka, Phys. Rev. B, 29, 6833 (1984), T. Chakraborty, Surf. Sci., 229, 16 (1990)