Spin-Orbit Scattering and Quantum Metallicity in Ultra-Thin Be Films

TL;DR

This study investigates how spin-orbit scattering influences the quantum metallic state in ultra-thin beryllium films, revealing that strong SOS suppresses the quantum metal phase at accessible magnetic fields.

Contribution

It demonstrates controlled introduction of spin-orbit scattering in Be films and shows its effect on the quantum metal phase in low-temperature magnetotransport.

Findings

Pure Be films show a quantum metal phase with R > R_Q and negative MR.

Adding Au to induce SOS diminishes the negative MR and the quantum metal phase.

Strong SOS shifts the quantum metal phase to higher magnetic fields beyond typical laboratory capabilities.

Abstract

We compare and contrast the low temperature magnetotransport properties of ultra-thin, insulating, Be films with and without spin-orbit scattering (SOS). Beryllium films have very little intrinsic SOS, but by "dusting" them with sub-monolayer coverages of Au, one can introduce a well controlled SOS rate. Pure Be films with sheet resistance R >R_Q exhibit a low-temperature negative magnetoresistance (MR) that saturates to the quantum resistance R_Q = h/e^2. This high-field quantum metal phase is believed to represent a new ground state of the system. In contrast, the corresponding negative MR in Be/Au films is greatly diminished, suggesting that, in the presence of strong SOS, the quantum metal phase can only be reached at field scales well beyond those typically available in a low temperature laboratory.