Fast long-wavelength exchange spin waves in partially-compensated Ga:YIG

Abstract

Spin waves in yttrium iron garnet (YIG) nano-structures attract increasing attention from the perspective of novel magnon-based data processing applications. For short wavelengths needed in small-scale devices, the group velocity is directly proportional to the spin-wave exchange stiffness constant ${\lambda }_{\mathrm{ex}}$. Using wave vector resolved Brillouin Light Scattering (BLS) spectroscopy, we directly measure ${\lambda }_{\mathrm{ex}}$ in Ga-substituted YIG thin films and show that it is about three times larger than for pure YIG. Consequently, the spin-wave group velocity overcomes the one in pure YIG for wavenumbers $k>4$ rad/$\mu$m, and the ratio between the velocities reaches a constant value of around 3.4 for all $k>20$ rad/$\mu$m. As revealed by vibrating-sample magnetometry (VSM) and ferromagnetic resonance (FMR) spectroscopy, Ga:YIG films with thicknesses down to 59 nm have a low Gilbert damping ($\alpha <10^{-3}$), a decreased saturation magnetization ${\mu }_0{M}_{\mathrm{S}}\approx 20$mT and a pronounced out-of-plane uniaxial anisotropy of about ${\mu }_0{H}_{\text{u1}}\approx 95$ mT which leads to an out-of-plane easy axis. Thus, Ga:YIG opens access to fast and isotropic spin-wave transport for all wavelengths in nano-scale systems independently of dipolar effects.

5 pages, 3 figures, 39 references, Supplemental material

References in corpus (3)

• Measurements of the exchange stiffness of YIG films by microwave resonance techniques
• Low damping and microstructural perfection of sub-40nm-thin yttrium iron garnet films grown by liquid phase epitaxy
• Long-range spin-wave propagation in transversely magnetized nano-scaled conduits

Cited by in corpus (1)

• Skyrmion-Excited Spin Wave Fractal Network