Weak antilocalization and disorder-enhanced electron interactions in crystalline GeSbTe

TL;DR

This study investigates quantum interference effects and electron interactions in crystalline GeSbTe thin films, revealing weak antilocalization, spin-orbit scattering, and various electron dephasing mechanisms across temperature ranges.

Contribution

It provides a detailed analysis of quantum transport phenomena and dephasing mechanisms in crystalline GeSbTe, a phase change material, which was not previously characterized in this manner.

Findings

Observation of weak antilocalization at low temperatures

Identification of spin-orbit scattering causing positive magnetoresistance

Determination of electron dephasing rates due to electron-phonon and electron-electron interactions

Abstract

Phase change materials can be reversibly switched between amorphous and crystalline states and often show strong contrast in the optical and electrical properties of these two phases. They are now in widespread use for optical data storage, and their fast switching and a pronounced change of resistivity upon crystallization are also very attractive for nonvolatile electronic data storage. Nevertheless there are still several open questions regarding the electronic states and charge transport in these compounds. In this work we study electrical transport in thin metallic films of the disordered, crystalline phase change material Ge$_1$Sb$_2$Te$_4$. We observe weak antilocalization and disorder enhanced Coulomb interaction effects at low temperatures, and separate the contributions of these two phenomena to the temperature dependence of the resistivity, Hall effect, and magnetoresistance. Strong spin-orbit scattering causes positive magnetoresistance at all temperatures, and a careful analysis of the low-field magnetoresistance allows us to extract the temperature dependent electron dephasing rate and study other scattering phenomena. We find electron dephasing due to inelastic electron-phonon scattering at higher temperatures, electron-electron scattering dephasing at intermediate temperatures, and a crossover to weak temperature dependence below 1 K.