Dzyaloshinskii-Moriya interaction and spin-orbit torque at the Ir/Co interface

Abstract

We studied the spin torque efficiency and the Dzyaloshinskii-Moriya interaction (DMI) of heterostructures that contain interface(s) of Ir and Co. The current-induced shifts of the anomalous Hall loops were used to determine the spin torque efficiency and DMI of [Pt/Co/X] multilayers (X=Ir, Cu) as well as Ir/Co and Pt/Ir/Co reference films. We find the effective spin Hall angle and the spin diffusion length of Ir to be ~0.01 and less than ~1 nm, respectively. The short spin diffusion length and the high conductivity make Ir an efficient spin sink layer. Such spin sink layer can be used to control the flow of spin current in heterostructures and to induce sufficient spin-orbit torque on the magnetic layer. The DMI of Ir and Co interface is found to be in the range of ~1.4 to ~2.2 mJ/m 2 , similar in magnitude to that of the Pt and Co interface. The Ir/Co and Pt/Co interfaces possess the same sign of DMI, resulting in a reduced DMI for the [Pt/Co/Ir] multilayers compared to that of the [Pt/Co/Cu] multilayers. These results show the unique role the Ir layer plays in defining spinorbit torque and chiral magnetism in thin film heterostructures.

Determination of spin Hall angle, spin mixing conductance, and spin diffusion length in CoFeB/Ir for spin-orbitronic devices

“…The value of spin diffusion length obtained for platinum is in agreement with the values found in the literature: the experimental values reported using the SP-FMR setup range from 0.5 nm [32] to 10 nm [23], with numerous values in between [10,48]. The obtained value l Ir s f = 1.3 nm is twice larger than the one presented in earlier studies [17,18] with similar FMR-based methods, and close to the one reported by spin-orbit torque technique, ∼ 1 nm [7]. That difference might be due to different Ir resistivity.…”

“…[17], with a 2% value, and twice the one reported by spin-orbit torque in Ref. [7]. The method that we present here enables us to make a comparison by getting rid of many artefacts that seem to be the cause of a broadening of the results obtained in the literature.…”

“…Iridium is a very promising material for spintronic applications. Its properties include large spin-orbit coupling [1], large Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange coupling [2], and strong interface contribution to perpendicular magnetic anisotropy (PMA) [3][4][5][6] and to interfacial Dzyaloshinskii-Moriya interaction [7]. Ir has been shown to be a key element as a spacer layer to create model perpendicular synthetic ferrimagnets or synthetic antiferromagnets [8,9].…”

“…Ir has been shown to be a key element as a spacer layer to create model perpendicular synthetic ferrimagnets or synthetic antiferromagnets [8,9]. However, to our knowledge, the spin Hall effect, which has proven to be an efficient physical effect to manipulate magnetization [10][11][12][13][14][15][16], was scarcely studied in Ir [7,17,18]. Given the scattering among the spin transport measurements, and spin-Hall effect (SHE) characterizations, we have decided to perform a comparative study.…”

Large spin-Hall effect in non-equilibrium binary copper alloys beyond the solubility limit

“…Cu-Ir [20][21][22][23][24] , Cu-Bi 25 , Cu-Pt [26][27][28] , Au-Pt 29,30 , and Au-W 31 . Cu-Ir system is an interesting SH material because neither Cu nor Ir exhibits remarkable SHE 32 . Niimi and co-workers 20 investigated the SHE of Ir-doped Cu with the Ir concentration range between 1% and 12%, which exhibited the large α SH of~2.1%.…”