Ultrathin Scale Tailoring of Anisotropic Magnetic Coupling and Anomalous Magnetoresistance in SrRuO₃−PrMnO₃ Superlattices

Abstract

A strong perpendicular magnetocrystalline anisotropy (PMA) in antiferromagnetically coupled SrRuO 3 (17 uc (unit cell))/PrMnO 3 (n uc) superlattices effectively reconstructs the interfacial spin ordering. The occurrence of significant anisotropic interfacial antiferromagnetic coupling between the Ru and Mn ions is systematically tuned by varying the PrMnO 3 layer thickness in ultrathin scale from 3 to 12 uc, which is associated with a rise in PMA energy from 0.28 × 10 6 to 1.60 × 10 6 erg/cm 3 . The analysis using the Stoner−Wohlfarth model and density functional theory confirm that the exchange anisotropy is the major contribution to the PMA. The superlattices with PrMnO 3 layer thickness ≥7 uc exhibit the tunneling-like transport of Ru 4d electrons, which is rather expected in the stronger antiferromagnetically coupled superlattices with thinner PrMnO 3 layer. Tunneling-like transport at thicker spacer layer in the SrRuO 3 −PrMnO 3 superlattice system is an unique feature of two ferromagnet-based superlattices. Our investigations show that the technologically important interfacial magnetic coupling, PMA, and tunneling magnetoresistance could be achieved in a periodically stacked bilayer and can be precisely manipulated by the size effect in ultrathin scale.

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.…”

Correlated Quantum Phenomena of Spin–Orbit Coupled Perovskite Oxide Heterostructures: Cases of SrRuO3 and SrIrO3 Based Artificial Superlattices

“…Table 2 summarizes the reported SrRuO 3 based superlattices with various functional partner compounds. [ 41,54,55,70,86–164 ] Herein, several emergent functionalities of SrRuO 3 based superlattices and their modulations are reviewed in the following Sections.…”