Berry Phase Engineering in SrRuO₃/SrIrO₃/SrTiO₃ Superlattices Induced by Band Structure Reconstruction

Abstract

The Berry phase, which reveals the intimate geometrical structure underlying quantum mechanics, plays a central role in the anomalous Hall effect. In this work, we observed a sign change of Berry curvatures at the interface between the ferromagnet SrRuO3 (SRO) layer and the SrIrO3 (SIO) layer with strong spin-orbit coupling. The negative Berry curvature at the interface, induced by the strongly spinorbit coupled Ir 5d bands near the Fermi level, makes the SRO/SIO interface different from the SRO layer that has a positive Berry curvature. These opposite Berry curvatures led to two anomalous Hall effect (AHE) channels with opposite signs at the SRO/SIO interface and in the SRO layer, respectively, resulting in a hump-like feature in the Hall resistivity loop. This observation offers a straightforward explanation of the hump-like feature that is usually associated with the chiral magnetic structure or magnetic skyrmions. Hence, this study provides evidence to oppose the widely accepted claiming that magnetic skyrmions induce the hump-like feature.

High‐Efficiency Magnon‐Mediated Magnetization Switching in All‐Oxide Heterostructures with Perpendicular Magnetic Anisotropy

“…[4,18,21,22,[35][36][37][38][39] Further, perpendicular magnetic anisotropy (PMA) can be obtained in the ferromagnetic SRO layer by carefully tuning the layer's thickness and the oxygen pressure during layer deposition. [29,[40][41][42][43] Therefore, in an SRO/NiO/SIO heterostructure, a spin current will be generated by an electric current flowing in the SIO layer through the spin Hall effect, thereby inducing a magnon current in the NiO layer. Finally, the induced magnon current will switch the magnetization in the SRO layer via magnon torque, as schematically shown in Figure 1b.…”

Tuning scalar spin chirality in ultrathin films of the kagome-lattice ferromagnet Fe3Sn

“…and SrRuO 3 -based perovskite multilayers and superlattices [24][25][26][27][28] , the impact of inhomogeneity on the occurrence of THE-like R yx anomalies has been argued. When AHE changes its sign depending on thickness as in the present system (Supplementary Fig.…”

Strain- and Oxygen-Modulated Anomalous Hall Effect in the SrRuO3/Sr3Al2O6 Heterostructure

“…SrRuO 3 (SRO), a 4d itinerant ferromagnet, is an extensively explored oxide with the nontrivial band structure, which is highly sensitive to the intrinsic Berry curvature, especially with the Fermi level near the band crossing position. − This nontrivial band structure triggers various exotic physical properties in SRO, including anomalous Hall effect (AHE), topological Hall effect (THE), and so forth. , Recently, the emergence of hump-like AHE in thin SRO films (few of nanometers) and heterostructures has garnered considerable attention as a promising signature of nontrivial spin texture as well as various potential applications in spintronics. − However, the origination of these hump-like features in AHE remains the subject of ongoing debate. − Some studies propose that these features arise from the topological Hall effect resulting from magnetic skyrmions (Berry curvature in band structure), − while the two-channel AHE (inhomogeneous magnetic domains) is suggested as the origination of hump-like AHE, , which is strongly related to thickness variation, , structural defects, and stoichiometric deviation (Ru contents). − In the two-channel AHE model, the two anomalous Hall resistances have opposite polarities, which are temperature dependent . Although hump-like features are observed in SRO films of varying thicknesses in the literature, such characteristics are typically observed in thinner films.…”

“…Although hump-like features are observed in SRO films of varying thicknesses in the literature, such characteristics are typically observed in thinner films. Such features are typically observed in thinner films (≤6 nm). − ,− The hump-like characteristics are absent in thick films unless they possess a high density of structural defects . Thus, a comprehensive investigation of AHE in SRO films is necessary to understand the origin of hump-like AHE.…”