Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 106: Transport, magnetotransport and quantum Hall physics

HL 106.4: Talk

Friday, March 20, 2015, 10:45–11:00, EW 202

Spin polarization of composite fermions in the N=0 Landau Level — •Lina Bockhorn¹, Dieter Schuh², Christian Reichl³, Werner Wegscheider³, and Rolf J. Haug¹ — ¹Institut für Festkörperphysik, Leibniz Universität Hannover, 30167 Hannover — ²Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93053 Regensburg — ³Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich

We study the fractional Quantum Hall effect (FQHE) in a high-mobility two-dimensional electron gas (2DEG) for different in-plane magnetic field components and by using a metallic topgate. Hall geometries are created by photolithography on a GaAs/GaAlAs quantum well containing a 2DEG. The high-mobility 2DEG has an electron density of n_e=3.2·10¹¹ cm⁻² and a mobility of µ_e=11.9·10⁶cm²/Vs.

Around the filling factor ν=3/2 we observe spin transitions of several fractional filling factors ν=8/5, 11/7, 13/9, 10/7, 7/5, and 4/3 [1, 2]. The FQHE is understood in terms of weakly interacting composite fermions (CF). The CF theory provides an understanding of the spin physics of the FQHE. We also observe spin polarization of the fractions ν=6/5 and ν=9/7 which arise from interacting CF [3].

[1] R. G. Clark et al., Phys. Rev. Lett. 62, 1536 (1989).

[2] R. R. Du et al., Phys. Rev. Lett. 75, 3926 (1995).

[3] Y. Liu et al., Phys. Rev. B 90, 085301 (2014).