Emergent ferromagnetism with tunable perpendicular magnetic anisotropy in short-periodic SrIrO3/SrRuO3 superlattices

Abstract

Interface engineering is a promising method to trigger emergent magnetic order in oxide heterostructures. Here, we report on the electrical and magnetic properties of short-periodic superlattices (SLs) (SrIrO3)n/(SrRuO3)n (n = 1–5) epitaxially grown on the (001)-oriented SrTiO3 substrate. Intriguingly, (SrIrO3)n/(SrRuO3)n superlattices show itinerant ferromagnetism with recovered Curie temperature and magnetic moment in spite of both individual components being antiferromagnetic insulators in ultrathin films (n ⩽ 3). Moreover, perpendicular magnetic anisotropy (PMA) is observed and can be tuned by the layer thickness n in the superlattices. Enhanced PMA as high as 1.6×106 erg/cm3 is obtained in the n = 1 superlattice, which is considerably higher compared to that in n = 4 and 5 SLs. Our systematic thickness-dependent studies reveal that the (SrIrO3)/(SrRuO3) interface plays a crucial role in both electrical and magnetic properties. These results indicate n as a knob to tune the PMA of superlattices, paving a way to design functional materials in transition metal oxides.

Lateral Modulation of Magnetic Anisotropy in Tricolor 3d–5d Oxide Superlattices

“…Magnetic anisotropy (MA) plays a key role in enriching the spectrum of physical responses and enabling high-performance spin devices. , It is important to develop effective strategies to manipulate the MA in magnetic systems, including changing magnetic easy-axis and MA energy (MAE). Transition metal oxides (TMOs) heterostructures and superlattices provide an intriguing playground for manipulation of electronic and magnetic properties. − Advances in thin-film fabricating techniques enable atomically precise fabrication of artificial heterostructures and superlattices comprising dissimilar oxides with strong magnetic and spin–orbital interactions, which are fundamentally important for achieving tunable and strong MA. − For instance, superlattices consisting of two different components, 3d oxide La 1– x Sr x MnO 3 (0 ≤ x ≤ 1) and 5d oxide SrIrO 3 (SIO), exhibit strong magnetic anisotropy with an enhanced magnitude from 10 5 to 10 6 erg/cm 3 . , To further modulate the magnetic easy-axis, two main approaches are developed through controlling the cation doping level in 3d La 1– x Sr x MnO 3 and the dimensionality of 5d SIO. ,, However, both approaches significantly weaken the magnetic interactions in La 1– x Sr x MnO 3 , thereby reducing the Curie temperature and magnetism dramatically. Moreover, changing the dimensionality in SIO will suppress the emergent Ir magnetization and the associated large single-ion anisotropy. − Therefore, it is challenging to achieve both strong MAE and tunable easy-axis only by adjusting the two components in these binary superlattices.…”

Coupling Charge and Topological Reconstructions at Polar Oxide Interfaces

“…The charge frustration arising from the interface with LaAlO 3 provides a unique opportunity for studying the effect of symmetry breaking on its momentum-space topology. Because of the insulating nature of LaAlO 3 , there is neither mixing of states at the Fermi energy nor interface-driven spin canting, as has been reported in, e.g., the SrRuO 3 =SrIrO 3 interface, which has been the topic of multiple studies in recent years [19,21,26,81,82]. In this sense, the system considered here offers a pleasing simplicity and a more direct approach toward controlling the topology in ultrathin SrRuO 3 and potentially other correlated metals.…”

Modulation of the Metal–Nonmetal Crossover in SrIrO3/CaMnO3 Superlattices

“…Reconstructions of charge, spin, and orbital states at transition-metal oxide interfaces give rise to exotic electronic states that are absent in their bulk counterparts. − Recently, 3d–5d heterostructures have attracted considerable attention due to the coupling between spin–orbit coupling (SOC) and electron–electron correlation (EEC), in which a variety of intriguing phenomena have been realized, including a Slater insulator phase, , perpendicular magnetic anisotropy, − topological Hall effect, − and spin–orbit torque. , For instance, by variation of the epitaxial strain, a Slater–Mott crossover has been observed in superlattices of (SrIrO 3 ) 1 /(SrTiO 3 ) 1 , tuning of chiral magnetic interactions by a change in the interfacial terminations has been realized in LaMnO 3 /SrIrO 3 (SIO) heterostructures, and a ferromagnetic state with T c ≈ 100 K could be induced in SIO via charge transfer at the LaCoO 3 /SIO interface …”