Nature of electrons from oxygen vacancies and polar catastrophe at LaAlO3/SrTiO3 interfaces

Abstract

The relative significance of quantum conductivity correction and magnetic nature of electrons in understanding the intriguing low-temperature resistivity minimum and negative magnetoresistance of the two-dimensional electron gas at LaAlO3/SrTiO3 interfaces has been a long outstanding issue since its discovery. Here we report a comparative magnetotransport study on amorphous and oxygen-annealed crystalline LaAlO3/SrTiO3 heterostructures at a relatively high-temperature range, where the orbital scattering is largely suppressed by thermal fluctuations. Despite of a predominantly negative out-of-plane magnetoresistance effect for both, the magnetotransport is isotropic for amorphous LaAlO3/SrTiO3 while strongly anisotropic and well falls into a two-dimensional quantum correction frame for annealed crystalline LaAlO3/SrTiO3. These results clearly indicate that a large portion of electrons from oxygen vacancies are localized at low temperatures, serving as magnetic centers, while the electrons from the polar field are only weakly localized due to constructive interference between time-reversed electron paths in the clean limit and no signature of magnetic nature is visible.

9 pages, 4 figures. Accepted in Journal of Physics: Condensed Matter

References in corpus (11)

• Magnetic effects at the interface between nonmagnetic oxides
• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Origin of charge density at LaAlO3-on-SrTiO3 hetero-interfaces; possibility of intrinsic doping
• Oxygen vacancies at titanate interfaces: two-dimensional magnetism and orbital reconstruction
• Weak-localization and spin-orbit interaction in side-gate field effect devices at the LaAlO${}_3$/SrTiO${}_3$ interface
• Growth-induced electron mobility enhancement at the LaAlO${}_3$/SrTiO${}_3$ interface
• Magnetic-field induced resistivity minimum with in-plane linear magnetoresistance of the Fermi liquid in SrTiO3-x single crystals
• Tuning the two-dimensional electron liquid at oxide interfaces by buffer-layer-engineered redox reactions
• A two-dimensional electron gas based on a 5s oxide with high room-temperature mobility and strain sensitivity
• Transport and thermoelectric properties of the LaAlO${}_3$/SrTiO${}_3$ interface
• Weak localization competes with the quantum oscillations in a natural electronic superlattice: the case of Na${}_{1.5}$(PO${}_2$)${}_4$(WO${}_3$)${}_{20}$

Cited by in corpus (1)

• Pressure-Induced Metal-Insulator and Paramagnet-Altermagnet Transitions in Rutile OsO2 Single Crystals