Magnetic Thin Films for Spintronics

Magnonics has shown the immense potential of compatibility with CMOS devices and the ability to be utilized in futuristic quantum computing. Therefore, the magnonic crystals, both metallic and insulating, are under extensive exploration. The presence of high spin-orbit interaction induced by the presence of rare-earth elements in thulium iron garnet (TmIG) increases its potential in magnonic applications. Previously, TmIG thin films were grown using ultra-high vacuum-based techniques. Here, we present a cost-effective solution-based approach that enables the excellent quality interface and surface roughness of the epitaxial TmIG/GGG. The deposited TmIG (12.2 nm) thin film's physical and spin dynamic properties are investigated in detail. The confirmation of the epitaxy using X-ray diffraction in -scan geometry along with the X-ray reflectivity and atomic force for the thickness and roughness analysis and topography, respectively. The epitaxial TmIG/GGG have confirmed the perpendicular magnetic anisotropy utilizing the polar-magneto-optic Kerr effect. Analyzing the ferromagnetic resonance study of TmIG/GGG thin films provides the anisotropy constant K = 20.610 0.210 N/m and the Gilbert damping parameter $\alpha$ = 0.0216 0.0028. The experimental findings suggest that the solution-processed TmIG/GGG thin films have the potential to be utilized in device applications.

In the quest to utilize rare-earth garnets (ReIG) with perpendicular magnetic anisotropy (PMA) in futuristic spintronics, the attention turned towards iron garnet thin films. Among this family, the one candidate is Tm3Fe5O12 (TmIG) that manifests PMA with excellent Gilbert damping, making this material a potential candidate in magnonics devices. Here, we report a cost-effective deposition approach of the TmIG thin films deposited on a thermally oxidized Si(100) substrate. The homogeneous TmIG (22 nm) thin film shows a roughness of 1.5 nm. The magnetic properties of thin films indicating the compensation temperature 15 K. Experimental findings present a method for the deposition of TmIG thin films, which is a potential candidate for fabricating futuristic compact devices.

YFeO12 (YIG) is a ferrimagnetic insulator that shows significant potential in various applications such as spin pumping and optical devices. In the case of YIG, the uncompensated antiferromagnetic coupled Fe3＋ ions originate the ferrimagnetic ordering. A homogeneous YIG thin film with lower Gilbert damping constant is essential for its industrial applications. Therefore, the YIG’s intrinsic and extrinsic magnetic energy dissipative factors are crucial to explore. Here, we report the growth of uniform polycrystalline YIG thin films on thermally oxidized Si (100) substrates. X-ray diffraction confirms the single-phase formation of YIG. Surface morphology and thickness on thin films are studied using scanning electron microscopy. X-ray photoemission is used to probe the valence state of constituent elements of the ferrimagnetic thin films with saturation magnetization 3.11 /f.u. The lowest Gilbert damping constant $\alpha$ = 4.754 × 10−3 with an inhomogeneous contribution to the linewidth of 5.04 mT is observed due to extrinsic inhomogeneous growth of the deposited films.

Topologically protected spin configurations are predicted to be the future of information storage and other computational applications. Through various investigations it has been proven that magnetic skyrmions consume a low driving current compare to magnetic domain wall, which can reduce the Joule heating significantly in memory storage devices and facilitate energy efficient, faster and miniaturized memory storage. Recently, numerous host materials are studied in condensed matter for exploiting the skyrmions. Experimentally magnetic multilayers consisting of repeated ferromagnetic (FM)/ heavy metal (HM) can stabilize interfacial skyrmions at near room temperature. In this seminal review, a brief introduction of the microscopic origin of the magnetic skyrmions with the theoretical models that have been used to simulate the interfacial skyrmions along with the important experimental techniques, which have been utilized to detect the interfacial skyrmions is presented. We also highlighted the progress on the potential applications of skyrmions in racetrack memory, logic gates, and neuromorphic devices.