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2Creation and study of thin-film heavy metal/ferro-(ferri)magnet nanostructures promising for spintronics
A. Telegin1*, V. Bessonova1, V. Teplov1, V. Bessonov1, S. Batalov1, I. Lobov1, M.E. Stebliy2, A. Ognev2'3, Y. Kim4, A. Samardak23
1-M.N. Mikheev Institute of Metal Physics, UB of RAS,620108, Yekaterinburg, S. Kovalevskaya str., 18 2- Far Eastern Federal University, 690922, Vladivostok, Ajax Bay, Russky Island 3- Sakhalin State University, 694420, Yuzhno-Sakhalinsk, Lenina str., 290 4- Korea University, Seoul, 02841, Republic of Korea
Being topologically protected skyrmions are regarded as the promising candidates for the role of information carriers in a new generation of energy efficient information processing technologies [1]. The presence of strong interfacial Dzyaloshinskii-Moriya interaction (iDMI) in ferromagnet/heavy metal (HM/FM) thin-film multilayers has significantly expanded the range of materials in which skyrmions can be created [2]. Throughout several comprehensive studies we theoretically and experimentally explored the evolution of iDMI and dynamics of skyrmions in two types of material systems: FM and ferrimagnetic (FiM) multilayers.
Samples of nanostructures with high perpendicular magnetic anisotropy were fabricated using magnetron sputtering techniques, and current-carrying structures with locally enhanced current density were also formed using ion-plasma etching and photolithography. Using vibration magnetometry, Kerr spectroscopy and electric-probe-measurements, the magnetic, magnetooptical and magnetotransport properties of thin-film nanostructures were studied. It was shown that all samples exhibit a magnetic response to current flow due to the Hall spin effect. The specific current-induced field parameters and the efficiency of current-induced switching were determined for the obtained nanostructures, as well as their dependence on the parameters of HM and FM layers. The maximum efficiency of current-induced processes was obtained in FiM alloys [3]. The Kerr microscopy demonstrates the presence of the domain structure and the magnetic skyrmions in the obtained samples. An estimation of the magnitude of the DMI was made based on the features of the domain structure behavior (e.g. asymmetric movement of chiral domain walls).
The laser spectroscopy experimental technique based on the Mandelstam-Brillouin light scattering (contactless spin-wave method) was employed to study the spin dynamics as well as estimation of iDMI in the samples. It was directly demonstrated that the magnitude of the shift, frequency and half-width of resonance lines in the spectra of spin waves of nanostructures closely correlate with the parameters of layers, type of the interface, and even the type of non-magnetic layer. A pronounced non-linear temperature dependence of the iDMI in FM/oxide nanostructures was observed for the first time.
Using micromagnetic modeling methods, the processes of magnetization reversal of nanostructures and the movement of skyrmions under the influence of electric and spin current in FM and FiM structures were studied. The influence of the DMI, damping, magnetic anisotropy, and magnetic fields on the speed of movement of skyrmions under the influence of AC/DC was also considered [4]. It was shown, the current-induced effects can be effectively used to control skyrmions in FiM metallic nanostructures.
Finally, the results showed that multi-sublattice ferrimagnetic films are a promising materials system, paving a path forward for the field of spintronics.
Support of the Russian Science Foundation № 21-72-20160 (https://rscf.ru/en/project/21-72-20160) and the Centre for the Collective Use of FEFU is acknowledged.
[1] A. Fert and F.N. Van Dau, Spintronics, from giant magnetoresistance to magnetic skyrmions and topological insulators, Comptes Rendus Physique, vol.20, pp. 817-831, (2019).
[2] J. Park, et al, Compositional gradient induced enhancement of Dzyaloshinskii-Moriya interaction in Pt/Co/Ta heterostructures modulated by Pt-Co alloy intralayers, Acta Materialia, vol.241, p. 118383, (2022).
[3] A. Telegin, V. Bessonov, I. Lobov, et al, Efficient current-induced magnetization reversal in metallic nanostructures, Physics of the Solid State, vol.12, p. 2158, (2023).
[4] A. Telegin, M. Stebliy, A. Ognev, et al, Dynamics of skyrmion textures in thin ferrimagnetic films, Indian J. Phys., (2024).
