Anomalous resistivity upturn in epitaxial L21-Co2MnAl films

TL;DR

This study investigates the low-temperature resistivity upturn in epitaxial L21-Co2MnAl films, revealing its independence from magnetic fields and linking it to electron-electron interactions influenced by structural disorder.

Contribution

It demonstrates controllable growth of high-spin-polarization films and identifies electron-electron interactions as the cause of resistivity upturn, providing new insights into disorder effects.

Findings

Resistivity upturn shows T1/2 dependence and is unaffected by magnetic fields.

Structural disorder influences electronic properties and resistivity behavior.

Electron-electron interactions are identified as the primary cause of the resistivity upturn.

Abstract

We report the controllable growth and the intriguing transport behavior of high-spin-polarization epitaxial L21-Co2MnAl films, which exhibit a low-temperature (T) resistivity upturn with pronounced T1/2 dependence, close relevance to structural disorder, and robust independence of magnetic fields. The resistivity upturn turns out to be qualitatively contradictory to weak localization, particle-particle channel electron-electron interaction (EEI), and orbital two-channel Kondo effect, leaving a three-dimensional particle-hole channel EEI the most likely physical source. Our result highlights a considerable tunability of the structural and electronic disorder of magnetic films by varying growth temperature, affording unprecedented insights into the spin polarization and the resistivity upturn.