Anomalous Resistance Ridges Along Filling Factor $\nu =4i$

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 $(\nu =4i)$ accompanied by suppression on either side of $\nu =4i$. This persists when either magnetic field or valley splitting is swept leading to resistance ridges running along $\nu =4i$. 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.

Accepted for publication in Phys. Rev. Lett

References in corpus (1)

• Valley Polarization in Si(100) at Zero Magnetic Field