Voltage control of interfacial magnetism has been greatly highlighted in spintronics research for many years, as it might enable ultra-low power technologies. Among few suggested approaches, magneto-ionic control of magnetism has demonstrated large modulation of magnetic anisotropy.Moreover, the recent demonstration of magneto-ionic devices using hydrogen ions presented relatively fast magnetization toggle switching, tsw ~ 100 ms, at room temperature. However, the operation speed may need to be significantly improved to be used for modern electronic devices.Here, we demonstrate that the speed of proton-induced magnetization toggle switching largely depends on proton-conducting oxides. We achieve ~1 ms reliable (> 10 3 cycles) switching using yttria-stabilized zirconia (YSZ), which is ~ 100 times faster than the state-of-the-art magneto-ionic devices reported to date at room temperature. Our results suggest further engineering of the protonconducting materials could bring substantial improvement that may enable new low-power computing scheme based on magneto-ionics.

Surface nanopatterns formed by ion beam sputtering (IBS) frequently include a high density of structural defects, which seriously limit their practical applications. Recent theoretical work [M. P. Harrison and R. M. Bradley, Phys. Rev. E 93, 040802(R) ( 2016)], based on the anisotropic Kuramoto-Sivashinsky (aKS) equation, proposes that rocking a substrate during IBS can produce defect-free patterns under certain requirements. We find experimentally, via low-energy Kr + irradiation of Si and amorphous carbon targets, that rocking the substrates generally improves the order of the ripple patterns. Indeed, order is improved even when conditions required in the aKS model are not satisfied. Through numerical simulations, we show that a suitable modification of this equation, in which conserved nonlinear effects are incorporated, reproduces satisfactorily the pattern order in our experimental conditions.

Nanopatterning at solid surfaces by ion beam sputtering (IBS) has been practiced mostly for stationary substrates with an ion beam incident under a fixed sputter geometry. We have released such constraints in the sputter condition. We simultaneously apply two ion beams or sequentially vary the orientation of substrate with respect to an ion beam. We also periodically change either the azimuthal or polar angle of the substrate with respect to an ion beam during IBS. These unconventional ways of IBS can improve the order of the pattern, and produce novel and non trivial nano patterns that well serve as touch stones to refine the theoretical models and thus deepen our understanding of the patterning mechanisms by IBS.