Spin-orbit-torque magnetization switching in a ferromagnetic SrRuO single layer with a spontaneous oxygen atomic displacement

堀内 皓斗*; 若林 勇希*; 荒木 康史; 家田 淳一; 山ノ内 路彦*; 他6名*

no journal, , 

Perovskite oxide SrRuO (SRO), which is also known as a ferromagnetic Weyl semimetal, is promising for realizing efficient spin-orbitronics devices. Here, we demonstrated an SOT-induced magnetization switching in a single-phased ferromagnetic SRO single layer. An important finding is that 7.5 10% of the magnetization in the 26 nm-thick SRO film was stably switched by the in-plane-current application. To clarify the reason for the obtained SOT in our SRO single layer, where spatial inversion symmetry seemingly is maintained, we closely analyzed the crystal structure using annular bright-field scanning transmission electron microscopy (ABF-STEM). We found that oxygen octahedral rotation (5 degrees) occurs especially near the interface between SRO and STO. By comparing the results with our theoretical calculation based on the tight-binding model, the observed partial single-layer magnetization switching can be attributed to the octahedral rotation and the associated large intrinsic spin Hall effect near the interface. We obtained a small switching current density of 3.1 5.3 MA cm, one order of magnitude smaller than conventional SOT systems consisting of a ferromagnet/heavy metal bilayer. This result implies that only a tiny spontaneous displacement of atoms in perovskite oxides plays a pivotal role in spin-orbitronics device applications.