Figure 1

(a) Semi-log $\theta$-$2\theta$ XRD scan of a 20-nm thick YIG film on GGG (111), which exhibits clear Laue oscillations corresponding to the film thickness. Inset: rocking curve of the YIG (444) peak. (b) Representative room-temperature FMR derivative spectrum of a 20-nm YIG film with $\mathit{H}$ in plane at $P_{\mathrm{rf}}=0.2\mathrm{mW}$, which gives a peak-to-peak linewidth of 10 Oe. (c) Schematics of experimental setup for ISHE voltage measurements for $\mathrm{Pt}/\mathrm{YIG}$ and $\mathrm{Pt}/\mathrm{\text{barrier}}/\mathrm{YIG}$ samples. (d) $V_{\mathrm{ISHE}}$ vs $H$ spectra and (e) FMR derivative spectrum of a $\mathrm{Pt}(5\mathrm{nm})/\mathrm{YIG}(20\mathrm{nm})$ bilayer at $P_{\mathrm{rf}}=200\mathrm{mW}$. The inset in (d) is the rf power dependence of $V_{\mathrm{ISHE}}$ with a least-squares fit. (f) Angular dependence of normalized $V_{\mathrm{ISHE}}$ of the $\mathrm{Pt}/\mathrm{YIG}$ bilayer (the green curve is a simple calculation of $\sin {\theta }_H$). (g) An AFM image of a 20-nm YIG film showing rms roughness of 0.15 nm over a $10\mu \mathrm{m}\times 10\mu \mathrm{m}$ area.Reuse & Permissions

Figure 2

$V_{\mathrm{ISHE}}$ vs $H$ (upper panel) and the corresponding FMR derivative spectra (lower panel) of $\mathrm{Pt}/\mathrm{\text{barrier}}/\mathrm{YIG}$ multilayers with 0.5-nm thick (a) ${\mathrm{Sr}}_2{\mathrm{GaTaO}}_6$, (b) ${\mathrm{SrTiO}}_3$, (c) ${\mathrm{Sr}}_2{\mathrm{CrNbO}}_6$, and (d) Si barriers at $P_{\mathrm{rf}}=200\mathrm{mW}$. The left inset in each upper panel shows the angular dependence of the normalized $V_{\mathrm{ISHE}}$ which exhibits the expected $\sin {\theta }_H$ (green curves) dependence on ${\theta }_H$, and the right inset shows the rf power dependence of $V_{\mathrm{ISHE}}$.Reuse & Permissions

Figure 3

Semi-log plots of $V_{\mathrm{ISHE}}$ normalized to the values for $\mathrm{Pt}/\mathrm{YIG}$ bilayers with direct contact as a function of the barrier thickness of (a) $\mathrm{Pt}/{\mathrm{Sr}}_2{\mathrm{GaTaO}}_6/\mathrm{YIG}$, (b) $\mathrm{Pt}/{\mathrm{SrTiO}}_3/\mathrm{YIG}$, (c) $\mathrm{Pt}/{\mathrm{Sr}}_2{\mathrm{CrNbO}}_6/\mathrm{YIG}$, and (d) $\mathrm{Pt}/\mathrm{Si}/\mathrm{YIG}$, with four representative $V_{\mathrm{ISHE}}$ vs $H$ spectra of various barrier thicknesses for each series shown in (e),(f),(g), and (h), respectively. The solid lines in (a), (b), (c), and (d) are least-squares fits, indicating the rate of exponential decay of ISHE voltages with decay length $\lambda =0.16$, 0.19, 0.23, and 0.74 nm for $\mathrm{Pt}/{\mathrm{Sr}}_2{\mathrm{GaTaO}}_6/\mathrm{YIG}$, $\mathrm{Pt}/{\mathrm{SrTiO}}_3/\mathrm{YIG}$, $\mathrm{Pt}/{\mathrm{Sr}}_2{\mathrm{CrNbO}}_6/\mathrm{YIG}$, and $\mathrm{Pt}/\mathrm{Si}/\mathrm{YIG}$, respectively.Reuse & Permissions

Figure 4

(a) Schematic of band structures of $\mathrm{Pt}/\mathrm{\text{barrier}}/\mathrm{YIG}$ heterostructures with an estimated Schottky barrier height ${\Phi }_B$ at half of the band gap for each barrier material. The blue curve illustrates the quantum tunneling of the electron wave function from Pt into the barrier. (b) Inverse of decay length, $1/\lambda$, as a function of $\sqrt{{\Phi }_B}$ for $\mathrm{Pt}/{\mathrm{Sr}}_2{\mathrm{GaTaO}}_6/\mathrm{YIG}$, $\mathrm{Pt}/{\mathrm{SrTiO}}_3/\mathrm{YIG}$, and $\mathrm{Pt}/{\mathrm{Sr}}_2{\mathrm{CrNbO}}_6/\mathrm{YIG}$, which includes three sets of values of ${\Phi }_B=0.45E_g$ (triangles), $0.50E_g$ (circles), and $0.55E_g$ (squares). The solid line connecting the three points and origin is a guide to the eye.Reuse & Permissions