The origin of insulating and non-ferromagnetic SrRuO3 monolayers

Abstract

The electro-magnetic properties of ultrathin epitaxial ruthenate films have long been the subject of debate. Here we combine experimental with theoretical investigations of (SrTiO3)5-(SrRuO3)n-(SrTiO3)5 (STO5-SROn-STO5) heterostructures with n = 1 and 2 unit cells, including extensive atomic-resolution scanning-transmission-electron-microscopy imaging, electron-energy-loss-spectroscopy chemical mapping, as well as transport and magneto-transport measurements. The experimental data demonstrate that the STO5-SRO2-STO5 heterostructure is stoichiometric, metallic, and ferromagnetic with TC ~ 128 K, even though it lacks the characteristic bulk-SRO octahedral tilts and matches the cubic STO structure. In contrast, the STO5-SRO1-STO5 heterostructure features Ru-Ti intermixing in the RuO2 layer, also without octahedral tilts, but is accompanied by a loss of metallicity and ferromagnetism. Density-functional-theory calculations show that stoichiometric n = 1 and n = 2 heterostructures are metallic and ferromagnetic with no octahedral tilts, while non-stoichiometry in the Ru sublattice in the n = 1 case opens an energy gap and induces antiferromagnetic ordering. Thus, the results indicate that the observed non-stoichiometry is the cause of the observed loss of metallicity and ferromagnetism in the n = 1 case.

arXiv comment20 pages, 9 figures

References in corpus (20)

• Magnetic effects at the interface between nonmagnetic oxides
• Why Some Interfaces Cannot be Sharp
• Electronic structure and magnetism in Ru based perovskites
• Transport Properties of the Kondo Lattice Model in the Limit $S=\infty$ and $D=\infty$
• Universality of the Mott-Ioffe-Regel limit in metals
• Metal-insulator transition in ultrathin LaNiO3 films
• Critical thickness for itinerant ferromagnetism in ultrathin films of SrRuO${}_3$
• Fundamental thickness limit of itinerant ferromagnetic SrRuO${}_3$ thin films
• Electronic properties of bulk and thin film SrRuO${}_3$: a search for the metal-insulator transition
• Quantum transport evidence of Weyl fermions in an epitaxial ferromagnetic oxide
• Spin chirality fluctuation in two-dimensional ferromagnets with perpendicular anisotropy
• Strain-stabilized superconductivity
• Dependence of electronic structure of SrRuO3 and the degree of correlation on cation off-stoichiometry
• Control of octahedral rotations in (LaNiO${}_3$)${}_n$/(SrMnO${}_3$)${}_m$ superlattices
• Highly-confined spin-polarized two-dimensional electron gas in SrTiO${}_3$/SrRuO${}_3$ superlattices
• Ferromagnetism and conductivity in atomically thin SrRuO3
• Correlation-driven eightfold magnetic anisotropy in a two-dimensional oxide monolayer
• Thickness-dependent magnetic properties and strain-induced orbital magnetic moment in SrRuO3 thin films
• A route to room temperature ferromagnetic ultrathin SrRuO${}_3$ films
• Strain induced metal-insulator transition in ultrathin films of SrRuO${}_3$

Cited by in corpus (7)

• Evolution of electronic band reconstruction in thickness-controlled perovskite SrRuO${}_3$ thin films
• Dimensionality Engineering of Magnetic Anisotropy from Anomalous Hall Effect in Synthetic SrRuO3 Crystals
• Ferromagnetic state with large magnetic moments realized in epitaxially strained Sr3Ru2O7 films
• Tuning Structural, Transport and Magnetic Properties of Epitaxial SrRuO3 through Ba-Substitution
• Single monolayer ferromagnetic perovskite SrRuO3 with high conductivity and strong ferromagnetism
• Anisotropy-driven interfacial magnetism in Ru-deficient SrRuO${}_3$ thin films
• Strain Engineering of van Hove Singularity and Coupled Itinerant Ferromagnetism in Quasi-2D Oxide Superlattices