09:30 〜 11:30
▲ [21a-P02-28] Low magnetic Gilbert damping in epitaxial films of FexCo1-x alloys
キーワード：spintronics material, spin dynamics
Magnetic Gilbert Damping is a critical parameter which has a strong influence on the required energy and operating speed of spintronics devices. In recent times, FeCo alloys were predicted to have ultralow magnetic damping by theoretical calculation. Fe75Co25 alloy already shows ultra-low damping, below 0.001, by experimental evidence but still, a large room is available for tuning the Gilbert damping and performing more detailed research using different measurement scheme. In this study, we investigate Gilbert damping in the epitaxial FexCo1-x alloy films with different alloy concentrations using both broadband ferromagnetic resonance (FMR) spectrometer as well as time-resolved magneto-optical Kerr effect (TRMOKE) microscope.
A 20-nm-thick FexCo1-x films were deposited at room temperature either on (100) MgO or MgAl2O4 (MAO) substrates using ultra-high vacuum magnetron sputtering system. All the films were capped by MgO/Cr layer which was deposited at room temperature. The nominal composition x was varied using co-sputtering techniques. Film crystalline structures were evaluated using X-ray diffraction (XRD) spectrometer. Magnetization measurements were performed using vibrating sample magnetometer (VSM). FMR measurements were performed using vector-network analyzer (VNA) with frequencies up to about 20 GHz. TRMOKE measurements were carried out using the standard pump-probe method. The damping value shows large anisotropy with respect to the crystalline axis, the minimum damping, about 0.002, is found around x = 0.2. This value is much larger than the ultralow damping value mentioned above. In the presentation, we will show the experimental data for the films deposited on MAO substrates and TRMOKE measurements.
A 20-nm-thick FexCo1-x films were deposited at room temperature either on (100) MgO or MgAl2O4 (MAO) substrates using ultra-high vacuum magnetron sputtering system. All the films were capped by MgO/Cr layer which was deposited at room temperature. The nominal composition x was varied using co-sputtering techniques. Film crystalline structures were evaluated using X-ray diffraction (XRD) spectrometer. Magnetization measurements were performed using vibrating sample magnetometer (VSM). FMR measurements were performed using vector-network analyzer (VNA) with frequencies up to about 20 GHz. TRMOKE measurements were carried out using the standard pump-probe method. The damping value shows large anisotropy with respect to the crystalline axis, the minimum damping, about 0.002, is found around x = 0.2. This value is much larger than the ultralow damping value mentioned above. In the presentation, we will show the experimental data for the films deposited on MAO substrates and TRMOKE measurements.