Interaction effects at the magnetic-field induced metal-insulator transition in Si/SiGe superlattices

TL;DR

This study investigates how in-plane magnetic fields induce a metal-insulator transition in Si/SiGe superlattices, highlighting the role of interaction effects, especially the spin-triplet term, in localization phenomena.

Contribution

It demonstrates that in-plane magnetic fields cause a metal-insulator transition in Si/SiGe superlattices and identifies the interaction-induced spin-triplet term as a key factor.

Findings

In-plane magnetic fields induce a metal-insulator transition.

Perpendicular magnetic fields do not cause localization.

Interaction effects, especially the spin-triplet term, influence localization.

Abstract

A metal-insulator transition was induced by in-plane magnetic fields up to 27 T in homogeneously Sb-doped Si/SiGe superlattice structures. The localisation is not observed for perpendicular magnetic fields. A comparison with magnetoconductivity investigations in the weakly localised regime shows that the delocalising effect originates from the interaction-induced spin-triplet term in the particle-hole diffusion channel. It is expected that this term, possibly together with the singlet particle-particle contribution, is of general importance in disordered n-type Si bulk and heterostructures.