Spin-Orbit Interaction and Kondo Scattering at the PrAlO$_3$/SrTiO$_3$ Interface: Effects of Oxygen Content

TL;DR

This study investigates how oxygen pressure during growth influences the electronic and magnetic properties of PrAlO$_3$/SrTiO$_3$ interfaces, revealing the interplay of spin-orbit interaction, Kondo scattering, and carrier dynamics.

Contribution

It demonstrates the effects of oxygen content on spin-orbit coupling and Kondo scattering, providing new insights into interface magnetotransport phenomena.

Findings

Resistivity increases with higher oxygen pressure.

Kondo behavior observed at low temperatures for certain oxygen pressures.

Magnetoresistance indicates strong spin-orbit interaction and Kondo effects.

Abstract

We report the effect of oxygen pressure during growth ($P_{O_{2}}$) on the electronic and magnetic properties of PrAlO$_3$ films grown on $\rm TiO_{2}$-terminated SrTiO$_3$ substrates. Resistivity measurements show an increase in the sheet resistance as $P_{O_{2}}$ is increased. The temperature dependence of the sheet resistance at low temperatures is consistent with Kondo theory for $P_{O_{2}} \ge 10^{-5}$ torr. Hall effect data exhibit a complex temperature dependence that suggests a compensated carrier density. We observe behavior consistent with two different types of carriers at interfaces grown at $P_{O_{2}} \ge 10^{-4}$ torr. For these interfaces, we measured a moderate positive magnetoresistance (MR) due to a strong spin-orbit (SO) interaction at low magnetic fields that evolves into a larger negative MR at high fields. Positive high MR values are associated with samples where a fraction of carriers are derived from oxygen vacancies. Analysis of the MR data permitted the extraction of the SO interaction critical field ( e.g. $ H_{SO}=$1.25 T for $P_{O_{2}}=10^{-5}$ torr). The weak anti-localization effect due to a strong SO interaction becomes smaller for higher $P_{O_{2}}$ grown samples, where MR values are dominated by the Kondo effect, particularly at high magnetic fields.