arXiv subjects

H. L. Stormer

Publications and source records attributed to H. L. Stormer.

40 records · Page 3Linked to original sources

arXiv1999

Exact Quantization of Even-Denominator Fractional Quantum Hall State at $ν$=5/2 Landau Level Filling Factor

We report ultra-low temperature experiments on the obscure fractional quantum Hall effect (FQHE) at Landau level filling factor $ν$=5/2 in a very high mobility specimen of $μ=1.7 \times 10^7$ cm$^2$/Vs. We achieve an electron temperature as low as $\sim$ 4~mK, where we observe vanishing $R_{xx}$ and, for the first time, a quantized Hall resistance, $R_{xy}=h/(5/2e^2)$ to within 2 ppm. $R_{xy}$ at the neighboring odd-denominator states $ν$=7/3 and 8/3 is also quantized. The temperature dependences of the $R_{xx}$-minima at these fractional fillings yield activation energy gaps $Δ_{5/2}$=0.11K, $Δ_{7/3}$=0.10K, and $Δ_{8/3}$=0.055K.

cond-mat.mes-hall↗

arXiv1999

Strongly Anisotropic Electronic Transport at Landau Level Filling Factor $ν= 9/2$ and $ν= 5/2$ Under Tilted Magnetic Field

We have investigated the influence of an increasing in-plane magnetic field on the states at half-filling of Landau levels ($ν$ = 11/2, 9/2, 7/2, and 5/2) of a two-dimensional electron system. In the electrically anisotropic phase at $ν$ = 9/2 and 11/2 an in-plane magnetic field of $\sim$ 1-2 T overcomes its initial pinning to the crystal lattice and {\it reorient} this phase. In the initially isotropic phases at $ν$ = 5/2 and 7/2 an in-plane magnetic field {\it induces} a strong electrical anisotropy. In all cases, for high in-plane fields, the high resistance axis is parallel to the direction of the in-plane field.

cond-mat.mes-hall↗

arXiv1998

Strongly Anisotropic Transport in Higher Two-Dimensional Landau Levels

Low-temperature, electronic transport in Landau levels N>1 of a two-dimensional electron system is strongly anisotropic. At half-filling of either spin level of each such Landau level the magnetoresistance either collapses to form a deep minimum or is peaked in a sharp maximum, depending on the in-plane current direction. Such anisotropies are absent in the N=0 and N=1 Landau level, which are dominated by the states of the fractional quantum Hall effect. The transport anisotropies may be indicative of a new many particle state, which forms exclusively in higher Landau levels.

cond-mat.mes-hall↗

arXiv1998

Effective Mass and g-Factor of Four Flux Quanta Composite Fermions

We investigate the properties of composite fermions with four attached flux quanta through tilted field experiments near Landau level filling factor nu = 3/4. The observed collapse of fractional quantum Hall gaps in the vicinity of this quarter-filling state can be comprehensively understood in terms of composite fermions with mass and spin. Remarkably, the effective mass and g-factor of these four flux quanta composite fermions around nu = 3/4 are very similar to those of two flux quanta composite fermions around nu = 3/2.

cond-mat.mes-hall↗