Anomalous state of a 2DEG in vicinal Si MOSFET in high magnetic fields

TL;DR

This paper reports an unusual state of a 2D electron gas in a vicinal Si MOSFET under high magnetic fields, characterized by anomalous conductivity behaviour linked to spin splitting collapse and influenced by magnetic field orientation.

Contribution

It identifies and characterizes a novel anomalous state in a 2DEG near a vicinal surface, revealing its dependence on magnetic fields and electron density.

Findings

Anomalous behaviour of conductivities $\sigma_{xx}$ and $\sigma_{xy}$ observed.

Collapse of Zeeman spin splitting associated with a large peak in $\sigma_{xx}$.

Effect is suppressed by parallel magnetic fields.

Abstract

We report the observation of an anomalous state of a 2D electron gas near a vicinal surface of a silicon MOSFET in high magnetic fields. It is characterised by unusual behaviour of the conductivities $\sigma_{xx}$ and $\sigma_{xy}$, which can be described as a collapse of the Zeeman spin splitting accompanied by a large peak in $\sigma_{xx}$ and an anomalous peak in $ \sigma_{xy}$. It occurs at densities corresponding to the position of the Fermi level above the onset of the superlattice mini-gap inherent to the vicinal system. The range of fields and densities where this effect exists has been determined, and it has been shown that it is suppressed by parallel magnetic fields.