title: Layer thickness dependence of the current-induced effective field vector in Ta|CoFeB|MgO.
abstract: Current-induced effective magnetic fields can provide efficient ways of electrically manipulating the magnetization of ultrathin magnetic heterostructures. Two effects, known as the Rashba spin orbit field and the spin Hall spin torque, have been reported to be responsible for the generation of the effective field. However, a quantitative understanding of the effective field, including its direction with respect to the current flow, is lacking. Here we describe vector measurements of the current-induced effective field in Ta|CoFeB|MgO heterostructrures. The effective field exhibits a significant dependence on the Ta and CoFeB layer thicknesses. In particular, a 1 nm thickness variation of the Ta layer can change the magnitude of the effective field by nearly two orders of magnitude. Moreover, its sign changes when the Ta layer thickness is reduced, indicating that there are two competing effects contributing to it. Our results illustrate that the presence of atomically thin metals can profoundly change the landscape for controlling magnetic moments in magnetic heterostructures electrically.
authors.affiliation: National Institute for Materials Science, Tsukuba 305-0047, Japan.
authors.forename: Junyeon
authors.initials: J
authors.lastname: Kim
authors.forename: Jaivardhan
authors.initials: J
authors.lastname: Sinha
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Hayashi
authors.forename: Michihiko
authors.initials: M
authors.lastname: Yamanouchi
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Fukami
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Seiji
authors.initials: S
authors.lastname: Mitani
authors.forename: Hideo
authors.initials: H
authors.lastname: Ohno