An investigation of the inverted Hanle effect in highly-doped Si

TL;DR

This study investigates the inverted Hanle effect in highly-doped silicon, revealing that its origin is not solely due to interfacial roughness and emphasizing the importance of non-local 4-terminal measurements for understanding spin transport.

Contribution

The paper demonstrates that the inverted Hanle effect's origin is more complex than previously thought and highlights the necessity of non-local 4-terminal schemes for accurate spin transport analysis in silicon.

Findings

No inverted Hanle signal in non-local 4-terminal scheme.

Inverted Hanle signal observed only in non-local 3-terminal scheme.

Two different Hanle signals identified in 3-terminal measurements.

Abstract

The underlying physics of the inverted Hanle effect appearing in Si was experimentally investigated using a Si spin valve, where spin transport was realized up to room temperature. No inverted-Hanle-related signal was observed in a non-local 4-terminal scheme even the same ferromagnetic electrode was used, whereas the signal was detected in a non-local 3-terminal scheme. Although the origin of the inverted Hanle effect has been thought to be ascribed to interfacial roughness beneath a ferromagnetic electrode, our finding is inconsistent with the conventional interpretation. More importantly, we report that there were two different Hanle signals in a non-local 3-terminal scheme, one of which corresponds to the inverted Hanle signal but the other is ascribed to spin transport. These results strongly suggest that (1) there is room for discussion concerning the origin of the inverted Hanle effect, and (2) achievement of spin transport in a non-local 4-terminal scheme is indispensable for further understanding of spin injection, spin transport and spin coherence in Si. Our new findings provide a new and strong platform for arising discussion of the physical essence of Hanle-related spin phenomena.