Tunable Two‐Channel Magnetotransport in SrRuO₃ Ultrathin Films Achieved by Controlling the Kinetics of Heterostructure Deposition

Abstract

In the field of oxide heterostructure engineering, there are extensive efforts to couple the various functionalities of each material. The Berry curvature‐driven magnetotransport of SrRuO3 ultrathin films is currently receiving a great deal of attention because it is extremely sensitive to the electronic structures near the Fermi surface driven by extensive physical parameters such as spin–orbit coupling and inversion symmetry breaking. Although this is beneficial in terms of heterostructure engineering, it renders transport behavior vulnerable to nanoscale inhomogeneity, resulting in artifacts called “hump anomalies.” Here, a method to tune the magnetotransport properties of SrRuO3 ultrathin films capped by LaAlO3 layers is developed. The kinetic process of pulsed laser deposition by varying the growth pressure during LaAlO3 layer deposition is systematically controlled. Furthermore, the effects of nanoscale inhomogeneity on the Berry curvature near the Fermi surface in SrRuO3 films are investigated. It is found that the high kinetic energy of the capping layer adatoms induces stoichiometric modification and nanoscale lattice deformation of the underlying SrRuO3 layer. The control of kinetics provides a way to modulate magnetization and the associated magnetotransport of the SrRuO3 layer.

Adsorption-Controlled Growth and Magnetism in Epitaxial SrRuO3 Films

“…Notably, a decrease in H c,2 coincides with an increase in RRR (Figure 1e), implying that the easier switching of the magnetization of this domain may be associated with a higher RRR. Since magnetization is sensitive to the structure, our hypothesis that there may be subtle structural changes in the films within the growth window from the distribution of pinning centers for magnetization switching (such as inhomogeneities at the nanoscale) due to the different growth conditions and kinetics 12,42 that are not captured by laboratory-based X-ray diffraction appears plausible.…”

Ferroelectric Proximity Effect and Topological Hall Effect in SrRuO3/BiFeO3 Multilayers

“…Moreover, van Thiel et al reported that charge discontinuity in the SRO/LaAlO 3 interface can result in the broken inversion symmetry, thus inducing both magnetic and topological reconstruction in the SRO layer. Nonetheless, the hump-like Hall signal may also result from SRO inhomogeneity and can be explained by a two-channel anomalous Hall effect (AHE) model. − Ren et al reported that the observed nonmonotonic anomalous Hall resistivity behavior in the BFO/SRO bilayer system can be attributed to SRO inhomogeneity instead of THE. Ko et al found that the stoichiometry and lattice deformation of the SRO layer can be manipulated by controlling the growth pressure of the LaAlO 3 capping layer, thus resulting in two-channel AHE signals.…”

“…23−26 Ren et al 25 observed nonmonotonic anomalous Hall resistivity behavior in the BFO/SRO bilayer system can be attributed to SRO inhomogeneity instead of THE. Ko et al 26 found that the stoichiometry and lattice deformation of the SRO layer can be manipulated by controlling the growth pressure of the LaAlO 3 capping layer, thus resulting in two-channel AHE signals.…”