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Anomalous Resistance Ridges Along Filling Factor $ν= 4i$

K. Takashina·M. Brun·T. Ota·D. K. Maude·A. Fujiwara·Y. Ono·Y. Takahashi·Y. Hirayama
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Abstract

We report anomalous structure in the magnetoresistance of SiO$_2$/Si(100)/SiO$_2$ quantum wells. When Landau levels of opposite valleys are driven through coincidence at the Fermi level, the longitudinal resistance displays elevations at filling factors that are integer multiples of 4 $(ν=4i)$ accompanied by suppression on either side of $ν=4i$. This persists when either magnetic field or valley splitting is swept leading to resistance ridges running along $ν=4i$. The range of field over which they are observed points to the role of spin degeneracy, which is directly confirmed by their disappearance under in-plane magnetic field. The data suggest a new type of many-body effect due to the combined degeneracy of valley and spin.

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K. Takashina, M. Brun, T. Ota, D. K. Maude, A. Fujiwara, Y. Ono, Y. Takahashi, Y. Hirayama. 2007-06-21. Anomalous Resistance Ridges Along Filling Factor $ν= 4i$. https://doi.org/10.1103/physrevlett.99.036803

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