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

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 $\mathrm{Ti}{\mathrm{O}}_2$-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.

8 pages, 5 figures

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