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TT: Fachverband Tiefe Temperaturen

TT 3: Topology: Quantum Hall Systems

TT 3.4: Talk

Monday, March 18, 2024, 10:15–10:30, H 2053

Current distribution in the quantum Hall regime — •Serkan Sirt¹, Matthias Kamm¹, Afif Siddiki², Vladimir Umansky³, and Stefan Ludwig¹ — ¹Paul-Drude-Inst. für Festkörperelektronik, Berlin — ²Istanbul Atlas Univ., Turkey — ³Weizmann Inst., Israel

The current distribution in the quantized Hall regime is of fundamental interest and important for applications. The widely appreciated Landauer-Büttiker picture (LBP) assumes chiral current flow along 1D, dissipation-less, compressible edge channels (EC). The screening theory [1] goes beyond the scope of the LBP by taking into account Coulomb interaction between electrons. It predicts dissipation-less current flow within incompressible strips (ICSs). The current-generating electric field is restricted to the Landau-gaped ICSs but fully screened elsewhere. As the magnetic field, B, is increased along a quantized Hall plateau, the ICSs move from the edge into the bulk of the Hall bar and thereby widen. Local potential measurements favor the screening theory [2] but direct current measurements are still missing.

Here, we present such direct current distribution measurements using a Hall bar including a small ohmic contact in its center, which does not disturb EC currents. Our measurements suggest EC current at the low B sides of the plateaus but clearly demonstrate bulk currents at higher B, while the Hall resistance remains quantized. Using multi-terminal measurements, we further confirm that both, edge and bulk currents, are chiral.

[1] R.R.Gerhardts, Phys. Stat. Sol. (b), 245 (2008) 378

[2] E. Ahlswede et al., Physica B 298 (2001) 562

Keywords: quantum hall effect; incompressible strips; chirality; magnetotransport